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RSS2015 Vol. 27, No. 02
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2015,
27: 024101.
doi: 10.11884/HPLPB201527.024101
Abstract:
Folded waveguide slow-wave structure as a traveling wave tubes main component is becoming smaller and smaller with vacuum electron devices operating frequency rises towards THz. And the fabrication tolerances are becoming increasingly critical. Traditional methods dont adapt to these micro-scale ranges. UV-LIGA is an attractive technique for fabricating this structure. This paper focuses on microfabrication techniques using SU8 photoresists to create this circuit at 220 GHz and a special mould made by PDMS and embedded polymer monofilament to assure the thickness and shape of the beam tunnel. By optimizing the process parameters, using gravity-assisted deposition technique, SU8 mold with coincident thickness and smooth surface is realized. After electroforming in a bath composed with sulfuric acid and copper sulfate and drawing out polymer monofilament, the microstructure is fabricated.
Folded waveguide slow-wave structure as a traveling wave tubes main component is becoming smaller and smaller with vacuum electron devices operating frequency rises towards THz. And the fabrication tolerances are becoming increasingly critical. Traditional methods dont adapt to these micro-scale ranges. UV-LIGA is an attractive technique for fabricating this structure. This paper focuses on microfabrication techniques using SU8 photoresists to create this circuit at 220 GHz and a special mould made by PDMS and embedded polymer monofilament to assure the thickness and shape of the beam tunnel. By optimizing the process parameters, using gravity-assisted deposition technique, SU8 mold with coincident thickness and smooth surface is realized. After electroforming in a bath composed with sulfuric acid and copper sulfate and drawing out polymer monofilament, the microstructure is fabricated.
2015,
27: 024102.
doi: 10.11884/HPLPB201527.024102
Abstract:
A novel 3-D fabrication process of micro-cupped resonators (MCR) using single-crystal diamond (SCD) is presented based on laser ablation. The high elastic modulus, low thermal elastic damping and large acoustic velocity of diamond make SCD an ideal material for micro and nanomechanical resonators. But diamond is difficult to shape for different application with the traditional machining method for its high hardness and chemical stability. Laser ablation is a better choice for higher accuracy, better structural symmetry, greater speed, and lower breakage rate. UV laser high precision processing machine has been employed for the ablation of SCD to study the effect of laser beam parameters on ablation quality. A better structure symmetry is acquired through optimized laser parameters, reasonably design of structure and trajectories of laser ablation so that the MCR has a potential advantage for micro-cupped gyroscope.
A novel 3-D fabrication process of micro-cupped resonators (MCR) using single-crystal diamond (SCD) is presented based on laser ablation. The high elastic modulus, low thermal elastic damping and large acoustic velocity of diamond make SCD an ideal material for micro and nanomechanical resonators. But diamond is difficult to shape for different application with the traditional machining method for its high hardness and chemical stability. Laser ablation is a better choice for higher accuracy, better structural symmetry, greater speed, and lower breakage rate. UV laser high precision processing machine has been employed for the ablation of SCD to study the effect of laser beam parameters on ablation quality. A better structure symmetry is acquired through optimized laser parameters, reasonably design of structure and trajectories of laser ablation so that the MCR has a potential advantage for micro-cupped gyroscope.
2015,
27: 024103.
doi: 10.11884/HPLPB201527.024103
Abstract:
Fabrication of microprobe integrated with a UV-curable adhesive, NOA73 microspheres and SU-8 micro pillars is presented, which can be applied to coordinate measurement machine (CMM) as a key component. The NOA73 microsphere is formed by the interfacial tension between NOA73 and other solution, the pillar is formed from SU-8 deep ultraviolet lithography. The glycerol is coated for compensating the refractive index difference between NOA73 and air, thus UV light still keep parallel, after propagating through the NOA73 microspheres. The high aspect ratio microprobe is obtained with the height above 1 200 m and the angle between micro-pillar and substrate is 89.
Fabrication of microprobe integrated with a UV-curable adhesive, NOA73 microspheres and SU-8 micro pillars is presented, which can be applied to coordinate measurement machine (CMM) as a key component. The NOA73 microsphere is formed by the interfacial tension between NOA73 and other solution, the pillar is formed from SU-8 deep ultraviolet lithography. The glycerol is coated for compensating the refractive index difference between NOA73 and air, thus UV light still keep parallel, after propagating through the NOA73 microspheres. The high aspect ratio microprobe is obtained with the height above 1 200 m and the angle between micro-pillar and substrate is 89.
2015,
27: 024104.
doi: 10.11884/HPLPB201527.024104
Abstract:
To enhance the output power of Terahertz (THz) Traveling-Wave Tubes (TWT), a new proposal about power combining of multiple signal is presented in the paper. Firstly, the design of D band Two-Beam Folded Waveguide Structure (TBFWS) was completed and the power divider was optimized. Then, a TBFWS was fabricated by micro milling, and its dimensions errors are below the designed values. Lastly, the cold-test and interaction characteristics of TBFWS were analyzed by CST code. The simulation results show theS11of TBFWS is below -20 dB, and the experiment results demonstrate the S11 of TBFWS is about -15 dB. The dispersion characteristics of the TBFWS show the circuit has a broad cold bandwidth of 22 GHz (16%) and 3 dB bandwidth of 12.5 GHz. With the 10 mW input peak power, 10 mA beam current and 15.79 kV beam voltage of each FW circuit, the gain and output power of single beam FW-TWT are 22 dB and 1.58 W at 0.14 THz, respectively, whereas, the TBFWS circuit can produce the combining output power of 2.91 W at 0.14 THz. Power combining efficiency of the circuits is more than 90%. The power combining method can efficiently enhance the output power of THz TWT.
To enhance the output power of Terahertz (THz) Traveling-Wave Tubes (TWT), a new proposal about power combining of multiple signal is presented in the paper. Firstly, the design of D band Two-Beam Folded Waveguide Structure (TBFWS) was completed and the power divider was optimized. Then, a TBFWS was fabricated by micro milling, and its dimensions errors are below the designed values. Lastly, the cold-test and interaction characteristics of TBFWS were analyzed by CST code. The simulation results show theS11of TBFWS is below -20 dB, and the experiment results demonstrate the S11 of TBFWS is about -15 dB. The dispersion characteristics of the TBFWS show the circuit has a broad cold bandwidth of 22 GHz (16%) and 3 dB bandwidth of 12.5 GHz. With the 10 mW input peak power, 10 mA beam current and 15.79 kV beam voltage of each FW circuit, the gain and output power of single beam FW-TWT are 22 dB and 1.58 W at 0.14 THz, respectively, whereas, the TBFWS circuit can produce the combining output power of 2.91 W at 0.14 THz. Power combining efficiency of the circuits is more than 90%. The power combining method can efficiently enhance the output power of THz TWT.
2015,
27: 024105.
doi: 10.11884/HPLPB201527.024105
Abstract:
The microstructure and properties of CuFe10 alloys irradiated by high current pulsed electron beam (HCPEB) with different pulse number were studied. The crater and Fe-rich spheres with diameter from 100 nm to 1 m existed on the remelting surface, which indicated that liquid phase separation occurred during HCPEB treatment. Compared with the initial sample, the microhardness and corrosion resistance of CuFe10 alloy after 30 pulses of HCPEB treatment were remarkably improved.It could be attributed to the liquid phase separation and grain refinement occurred on the surface of CuFe10 alloy in the process of rapid remelting and solidification induced by HCPEB.
The microstructure and properties of CuFe10 alloys irradiated by high current pulsed electron beam (HCPEB) with different pulse number were studied. The crater and Fe-rich spheres with diameter from 100 nm to 1 m existed on the remelting surface, which indicated that liquid phase separation occurred during HCPEB treatment. Compared with the initial sample, the microhardness and corrosion resistance of CuFe10 alloy after 30 pulses of HCPEB treatment were remarkably improved.It could be attributed to the liquid phase separation and grain refinement occurred on the surface of CuFe10 alloy in the process of rapid remelting and solidification induced by HCPEB.
2015,
27: 024106.
doi: 10.11884/HPLPB201527.024106
Abstract:
Optical lithography is widely used in the micro-electro-mechanical system (MEMS) and integrated circuit. As the lithographic process equipment is very expensive, it is critical to utilize optical lithography simulation to predict the useful results and optimize process problems. In this paper, the waveguide (WG) method based on rigorous electromagnetic field model is presented. It is firstly extended to simulate the thick photoresist exposure in MEMS field. By applying this model, the light intensity distribution in the photoresist can be simulated. Thus, the morphology of photoresist after development can be predicted. Some examples demonstrate the validity of this model.
Optical lithography is widely used in the micro-electro-mechanical system (MEMS) and integrated circuit. As the lithographic process equipment is very expensive, it is critical to utilize optical lithography simulation to predict the useful results and optimize process problems. In this paper, the waveguide (WG) method based on rigorous electromagnetic field model is presented. It is firstly extended to simulate the thick photoresist exposure in MEMS field. By applying this model, the light intensity distribution in the photoresist can be simulated. Thus, the morphology of photoresist after development can be predicted. Some examples demonstrate the validity of this model.
2015,
27: 024107.
doi: 10.11884/HPLPB201527.024107
Abstract:
The occurrence of the groove wear on the flank face of diamond cutting tool makes a serious impact on the quality of the finish surface of the workpiece. In order to reveal the growth and extension mechanism of the groove wear from the perspective of graphitization, the molecular dynamics (MD) model of diamond cutting tool with initial groove on the flank face is established, and the motion of the workpiece material and the change of crystal structure of the diamond cutting tool are simulated. The results show that the motion of the workpiece material changes for the existence of the initial groove, and the temperature and the energy of the atoms increase in the cutting process, nearly 8% for the temperature and 1.4% for the energy. The analyses of crystal structure and the radial distribution function of the diamond cutting tool show that there is a diamond-graphite transformation on the initial groove. The change of the graphitization conversion with cutting time is studied through bond angle calculation. The graphitization conversion rate increases with cutting time, when the cutting process proceeds to the stable stage, the graphitization conversion rate tends to be stable at nearly 6%.
The occurrence of the groove wear on the flank face of diamond cutting tool makes a serious impact on the quality of the finish surface of the workpiece. In order to reveal the growth and extension mechanism of the groove wear from the perspective of graphitization, the molecular dynamics (MD) model of diamond cutting tool with initial groove on the flank face is established, and the motion of the workpiece material and the change of crystal structure of the diamond cutting tool are simulated. The results show that the motion of the workpiece material changes for the existence of the initial groove, and the temperature and the energy of the atoms increase in the cutting process, nearly 8% for the temperature and 1.4% for the energy. The analyses of crystal structure and the radial distribution function of the diamond cutting tool show that there is a diamond-graphite transformation on the initial groove. The change of the graphitization conversion with cutting time is studied through bond angle calculation. The graphitization conversion rate increases with cutting time, when the cutting process proceeds to the stable stage, the graphitization conversion rate tends to be stable at nearly 6%.
2015,
27: 024108.
doi: 10.11884/HPLPB201527.024108
Abstract:
The micro plane explosion switch applied in the exploding foil initiator system consists of two main electrodes and one trigger electrode. An investigation on the influence of Al/CuO reactive multilayer films (RMFs) additives on the trigger electrode was performed. The trigger electrode has been characterized with scanning electron microscopy, differential scanning calorimetry and the atomic emission spectroscopy double line technique. The heat released in the thermite reaction between Al film and CuO film was found to be 1537 J/g. The reaction temperature curves reached to the peak in about 0.5 s, and then dropped to a relatively stable temperature. Firing characteristics of the switch were accomplished using the designed experiment set up. The result shows that the peak and rise time of the discharge current were 1938 A and 390 ns for Cu/Al/CuO RMFs when main voltage was 2000 V, which was better than the trigger electrode only consisted of Cu film.
The micro plane explosion switch applied in the exploding foil initiator system consists of two main electrodes and one trigger electrode. An investigation on the influence of Al/CuO reactive multilayer films (RMFs) additives on the trigger electrode was performed. The trigger electrode has been characterized with scanning electron microscopy, differential scanning calorimetry and the atomic emission spectroscopy double line technique. The heat released in the thermite reaction between Al film and CuO film was found to be 1537 J/g. The reaction temperature curves reached to the peak in about 0.5 s, and then dropped to a relatively stable temperature. Firing characteristics of the switch were accomplished using the designed experiment set up. The result shows that the peak and rise time of the discharge current were 1938 A and 390 ns for Cu/Al/CuO RMFs when main voltage was 2000 V, which was better than the trigger electrode only consisted of Cu film.
2015,
27: 024109.
doi: 10.11884/HPLPB201527.024109
Abstract:
The electro-optic modulator is an important component in the optical interconnected system, which plays a role in controlling optical signal by electrical pulse. The 3 dB bandwidth is a representative performance parameter that determines the maximum amount of information that can be carried in the input light. An electro-absorption optical modulator concept based upon a dual-graphene layer is presented. The device consists of a silicon-on-insulator micro-ring waveguide resonator upon which two graphene layers reside, separated by a thin insulating region. The lower graphene acts as a tunable absorber, while the upper layer functions as a transparent gate electrode. Calculations based upon realistic graphene material properties and the optical path amplification of micro-ring waveguide resonator show that 3 dB bandwidths over 100 GHz are achievable at near =1.55 m. In addition, the structure of micro-ring waveguide resonator can be easily integrated with optical Wavelength Division Multiplexing(WDM) interconnection system, so as to enhance the degree of integration and reduce technical complexity.
The electro-optic modulator is an important component in the optical interconnected system, which plays a role in controlling optical signal by electrical pulse. The 3 dB bandwidth is a representative performance parameter that determines the maximum amount of information that can be carried in the input light. An electro-absorption optical modulator concept based upon a dual-graphene layer is presented. The device consists of a silicon-on-insulator micro-ring waveguide resonator upon which two graphene layers reside, separated by a thin insulating region. The lower graphene acts as a tunable absorber, while the upper layer functions as a transparent gate electrode. Calculations based upon realistic graphene material properties and the optical path amplification of micro-ring waveguide resonator show that 3 dB bandwidths over 100 GHz are achievable at near =1.55 m. In addition, the structure of micro-ring waveguide resonator can be easily integrated with optical Wavelength Division Multiplexing(WDM) interconnection system, so as to enhance the degree of integration and reduce technical complexity.
2015,
27: 024111.
doi: 10.11884/HPLPB201527.024111
Abstract:
In order to obtain the uniform inverted pyramid micro-structures on the surface of multi-crystalline silicon, this paper presents a new way of using two orthogonal ultrasonic standing waves exerted dimensionally to assist wet chemical erosion and improve the performance of light trapping. A 2D geometrical mode of grid-like arrangements is established firstly after some comparison. Then the theory of particles aggregation motion formatting the grid-like model under the field of ultrasonic standing waves is studied and verified with simulation tool. Experiments are carried out to test the effects of particles controlled motion. The multi-crystalline silicon erosion results illustrate that the idea of application of ultrasonic standing waves on grid micromachining is feasible and excellent.
In order to obtain the uniform inverted pyramid micro-structures on the surface of multi-crystalline silicon, this paper presents a new way of using two orthogonal ultrasonic standing waves exerted dimensionally to assist wet chemical erosion and improve the performance of light trapping. A 2D geometrical mode of grid-like arrangements is established firstly after some comparison. Then the theory of particles aggregation motion formatting the grid-like model under the field of ultrasonic standing waves is studied and verified with simulation tool. Experiments are carried out to test the effects of particles controlled motion. The multi-crystalline silicon erosion results illustrate that the idea of application of ultrasonic standing waves on grid micromachining is feasible and excellent.
2015,
27: 024112.
doi: 10.11884/HPLPB201527.024112
Abstract:
A systematic investigation on the microstructure, optical, and magnetic properties of Co-doped ZnO films is reported. Zn1-xCoxO films were synthesized using magnetron sputtering technique, which could produce economically feasible large area films with good crystalline properties even at a low substrate temperature. Structural analysis indicates that the wurtzite ZnO crystal can be well retained up to a Co composition of atom fraction 8%. All the samples show high transparency in the visible region. There are three absorption bands located on 567, 615, and 659 nm in the optical transmittance spectra for Co doped ZnO films, which correspond to the electronic transition of Co 3d orbitals in the oxygen tetrahedron, showing the incorporation of Co into the Zn sites in the wurtzite ZnO host lattice. The magnetic measurements indicate that all the Co doped ZnO films are ferromagnetic at room temperature and the concentration of Co doping plays an important role in the magnetic properties of Zn1-xCoxO thin films. Considering the structural, electrical, and magnetic investigations, the ferromagnetism observed in our samples should be an intrinsic property of Co doped ZnO films and can be described by bound magnetic polarons models with respect to defect-bound carriers.
A systematic investigation on the microstructure, optical, and magnetic properties of Co-doped ZnO films is reported. Zn1-xCoxO films were synthesized using magnetron sputtering technique, which could produce economically feasible large area films with good crystalline properties even at a low substrate temperature. Structural analysis indicates that the wurtzite ZnO crystal can be well retained up to a Co composition of atom fraction 8%. All the samples show high transparency in the visible region. There are three absorption bands located on 567, 615, and 659 nm in the optical transmittance spectra for Co doped ZnO films, which correspond to the electronic transition of Co 3d orbitals in the oxygen tetrahedron, showing the incorporation of Co into the Zn sites in the wurtzite ZnO host lattice. The magnetic measurements indicate that all the Co doped ZnO films are ferromagnetic at room temperature and the concentration of Co doping plays an important role in the magnetic properties of Zn1-xCoxO thin films. Considering the structural, electrical, and magnetic investigations, the ferromagnetism observed in our samples should be an intrinsic property of Co doped ZnO films and can be described by bound magnetic polarons models with respect to defect-bound carriers.
2015,
27: 024113.
doi: 10.11884/HPLPB201527.024113
Abstract:
A simple, low cost and high yield method for the fabrication of silicon tip array for potential use in microelectronic applications is proposed. Both anisotropic and isotropic wet chemical etching methods are studied. The etching mechanism, etching rate and the shape of silicon tip in different solutions are analyzed by scanning electron microscope (SEM). The results show that the undercutting rate is dramatically reduced because of adding I2 and KI in 40% mass fraction KOH solution, and a rocket tip on the upper part of silicon tip is obtained. The shape ofsilicon tip etched in HNA looks like Eiffel Tower, and the radius of curvature is less than 15 nm. This silicon tip array has been successfully integrated into the fabrication of vacuum microelectronic accelerometer.
A simple, low cost and high yield method for the fabrication of silicon tip array for potential use in microelectronic applications is proposed. Both anisotropic and isotropic wet chemical etching methods are studied. The etching mechanism, etching rate and the shape of silicon tip in different solutions are analyzed by scanning electron microscope (SEM). The results show that the undercutting rate is dramatically reduced because of adding I2 and KI in 40% mass fraction KOH solution, and a rocket tip on the upper part of silicon tip is obtained. The shape ofsilicon tip etched in HNA looks like Eiffel Tower, and the radius of curvature is less than 15 nm. This silicon tip array has been successfully integrated into the fabrication of vacuum microelectronic accelerometer.
2015,
27: 024114.
doi: 10.11884/HPLPB201527.024114
Abstract:
A special microneedle is employed to prepare an ultrafine Ar/O2 atmospheric pressure plasma jet source device. When a high voltage of 4.0 kV is applied to the electrodes, this device can generate stable and almost homogeneous plasma jet, and its line width is on the order of tens of micrometers.Additionally, the ability of ultrafine Ar/O2 plasma jet to selectively remove parylene-C film is also investigated. Experimental results indicate that this ultrafine Ar/O2 plasma jet can effectively remove parylene-C film and the removal rate reaches 2.4 m/min. Therefore, this Ar/O2 atmospheric pressure plasma jet have the potential of being used to the ultrafine process for future material processing.
A special microneedle is employed to prepare an ultrafine Ar/O2 atmospheric pressure plasma jet source device. When a high voltage of 4.0 kV is applied to the electrodes, this device can generate stable and almost homogeneous plasma jet, and its line width is on the order of tens of micrometers.Additionally, the ability of ultrafine Ar/O2 plasma jet to selectively remove parylene-C film is also investigated. Experimental results indicate that this ultrafine Ar/O2 plasma jet can effectively remove parylene-C film and the removal rate reaches 2.4 m/min. Therefore, this Ar/O2 atmospheric pressure plasma jet have the potential of being used to the ultrafine process for future material processing.
2015,
27: 024115.
doi: 10.11884/HPLPB201527.024115
Abstract:
To solve the problem of cross sensitivity of fiber Bragg grating (FBG), a novel FBG temperature-compensated method is proposed by using a single FBG adopting a special compensated method. The basic operating principle of the temperature compensation exploited in this study is based on the material thermal stress. The relationship between strain and temperature response of FBG is theoretically analyzed. The analysis results show that the temperature and strain sensitivity coefficient should be accurately measured, the errors of mechanical process have quite great influence on the temperature-compensated results, and the cross section ratio of strain element to temperature compensated element should be less than 0.5, the length ratio of strain element to temperature compensated element can negligibly affect the temperature-compensated results. Thus, it is anticipated that length ratio should be increased as soon as possible on the base of non-influence on the temperature-compensated results.
To solve the problem of cross sensitivity of fiber Bragg grating (FBG), a novel FBG temperature-compensated method is proposed by using a single FBG adopting a special compensated method. The basic operating principle of the temperature compensation exploited in this study is based on the material thermal stress. The relationship between strain and temperature response of FBG is theoretically analyzed. The analysis results show that the temperature and strain sensitivity coefficient should be accurately measured, the errors of mechanical process have quite great influence on the temperature-compensated results, and the cross section ratio of strain element to temperature compensated element should be less than 0.5, the length ratio of strain element to temperature compensated element can negligibly affect the temperature-compensated results. Thus, it is anticipated that length ratio should be increased as soon as possible on the base of non-influence on the temperature-compensated results.
2015,
27: 024110.
doi: 10.11884/HPLPB201527.024110
Abstract:
In order to understand the basic principle of ultraviolet induced nanoparticle colloid jet machining and efficiently create ultra-smooth surface of brittle crystals, the properties of ultraviolet-visible beam propagation in TiO2 nanoparticle colloid was studied. The ultraviolet-visible beam before and after transmitting through various concentration and absorption layer thickness of TiO2 nanoparticle colloid was measured by an optical power meter. The attenuation characteristics of ultraviolet-visible beam were obtained by measurement experiment based on the theoretical analysis of light absorption and scattering in colloid. Investigation results indicate that, in order to ensure sufficient intensity of ultraviolet light to transmit through TiO2 nanoparticle colloid and irradiate on the work surface in ultraviolet induced nanoparticle colloid jet machining, the colloid concentration should be controlled less than 500 mol/m3, the absorption layer thickness of light-colloid coupling region should not exceed 20 mm.
In order to understand the basic principle of ultraviolet induced nanoparticle colloid jet machining and efficiently create ultra-smooth surface of brittle crystals, the properties of ultraviolet-visible beam propagation in TiO2 nanoparticle colloid was studied. The ultraviolet-visible beam before and after transmitting through various concentration and absorption layer thickness of TiO2 nanoparticle colloid was measured by an optical power meter. The attenuation characteristics of ultraviolet-visible beam were obtained by measurement experiment based on the theoretical analysis of light absorption and scattering in colloid. Investigation results indicate that, in order to ensure sufficient intensity of ultraviolet light to transmit through TiO2 nanoparticle colloid and irradiate on the work surface in ultraviolet induced nanoparticle colloid jet machining, the colloid concentration should be controlled less than 500 mol/m3, the absorption layer thickness of light-colloid coupling region should not exceed 20 mm.
2015,
27: 024116.
doi: 10.11884/HPLPB201527.024116
Abstract:
The integrated resonator fiber optic gyroscope (RFOG) using a hollow core photonic bandgap fiber (HCPBF) is realized. The coupling structure of the resonator is designed and fabricated based on the micro-optical structure. The definition of the resonator is experimentally measured to be 3.7. The gyroscope system based on this kind of resonator is constructed and its responses corresponding to the stationary and rotational states are tested experimentally. The results show that the maximum observed peak to peak drift over a 60 s measurement and the long-term drift over 1 h measurement are 2.45 ()/s and 7.11 ()/s, respectively. In addition, the gyroscope outputs of 50 ()/s (integral time: 10 s) and 100 ()/s (integral time: 10 s) are obtained by using the proposed simulating turntable experiment and the Sagnac effect of our gyroscope system is demonstrated. The coupling loss is the main factor to influence the performance of the gyroscope by analysis. For the resonator structure we proposed, it is possible and feasible to apply in the gyroscope system.
The integrated resonator fiber optic gyroscope (RFOG) using a hollow core photonic bandgap fiber (HCPBF) is realized. The coupling structure of the resonator is designed and fabricated based on the micro-optical structure. The definition of the resonator is experimentally measured to be 3.7. The gyroscope system based on this kind of resonator is constructed and its responses corresponding to the stationary and rotational states are tested experimentally. The results show that the maximum observed peak to peak drift over a 60 s measurement and the long-term drift over 1 h measurement are 2.45 ()/s and 7.11 ()/s, respectively. In addition, the gyroscope outputs of 50 ()/s (integral time: 10 s) and 100 ()/s (integral time: 10 s) are obtained by using the proposed simulating turntable experiment and the Sagnac effect of our gyroscope system is demonstrated. The coupling loss is the main factor to influence the performance of the gyroscope by analysis. For the resonator structure we proposed, it is possible and feasible to apply in the gyroscope system.
2015,
27: 024117.
doi: 10.11884/HPLPB201527.024117
Abstract:
Film bulk acoustic resonator (FBAR) force sensor is regarded as a new type of resonant sensor ,whose design is based on force-frequency characteristics of FBAR. This paper aims to analyze the force-frequency characteristics of FBAR that works in the longitudinal mode and adopts wurtzite AlN as piezoelectric thin film, whose resonance frequency shift results from the elastic constant under the stress load by taking an FBAR micro-accelerometer as an example. First, the stress distribution of the piezoelectric thin film of FBAR which integrated on FBAR micro-accelerometer under the inertial forces was obtained from applying the static simulation of finite element analysis. Then the maximum stress value selected as stress load, combining first principles to calculate the relation ship between elastic coefficient and stress of wurtzite AlN, so that the maximum variation of AlN elastic coefficient under the stress load can be predicted. Next, the resonance frequency with shift properties of FBAR micro-accelerometer are compared under different stress loads with the analysis result of harmonic response so as to predict the frequency characteristics and tendency of FBAR. By analyzing FBAR under the stress loads, its resonance frequency can be concluded to shifts to a higher one, and FBAR micro-accelerometer sensitivity is about kHz/g, which indicates the good linearity of acceleration increment-frequency shift characteristic curve.
Film bulk acoustic resonator (FBAR) force sensor is regarded as a new type of resonant sensor ,whose design is based on force-frequency characteristics of FBAR. This paper aims to analyze the force-frequency characteristics of FBAR that works in the longitudinal mode and adopts wurtzite AlN as piezoelectric thin film, whose resonance frequency shift results from the elastic constant under the stress load by taking an FBAR micro-accelerometer as an example. First, the stress distribution of the piezoelectric thin film of FBAR which integrated on FBAR micro-accelerometer under the inertial forces was obtained from applying the static simulation of finite element analysis. Then the maximum stress value selected as stress load, combining first principles to calculate the relation ship between elastic coefficient and stress of wurtzite AlN, so that the maximum variation of AlN elastic coefficient under the stress load can be predicted. Next, the resonance frequency with shift properties of FBAR micro-accelerometer are compared under different stress loads with the analysis result of harmonic response so as to predict the frequency characteristics and tendency of FBAR. By analyzing FBAR under the stress loads, its resonance frequency can be concluded to shifts to a higher one, and FBAR micro-accelerometer sensitivity is about kHz/g, which indicates the good linearity of acceleration increment-frequency shift characteristic curve.
2015,
27: 024118.
doi: 10.11884/HPLPB201527.024118
Abstract:
The resonant cavity with p-i-n structure, which is to enhance the quantum efficiency of lateral photoelectric effect, is designed for position sensitive detector. The top mirror is a one-dimensional defect photonic crystal, and the bottom mirror is a distributed Bragg reflector (DBR), while the part of between the two mirrors is the active medium. The transmission of defect photonic crystal is obtained by transform matrix method. Because of the high reflectivity of top and bottom structures, the transmitted resonant guided mode of defect photonic crystal would be limited in active medium. The quantum efficiency of active medium is deduced by analyzing the equivalent mode of resonant cavity. The results of numerical simulation show that the quantum efficiency is enhanced by the resonant guided mode.
The resonant cavity with p-i-n structure, which is to enhance the quantum efficiency of lateral photoelectric effect, is designed for position sensitive detector. The top mirror is a one-dimensional defect photonic crystal, and the bottom mirror is a distributed Bragg reflector (DBR), while the part of between the two mirrors is the active medium. The transmission of defect photonic crystal is obtained by transform matrix method. Because of the high reflectivity of top and bottom structures, the transmitted resonant guided mode of defect photonic crystal would be limited in active medium. The quantum efficiency of active medium is deduced by analyzing the equivalent mode of resonant cavity. The results of numerical simulation show that the quantum efficiency is enhanced by the resonant guided mode.
2015,
27: 024119.
doi: 10.11884/HPLPB201527.024119
Abstract:
In order to effectively prompt the resonance frequency and the quality factor of atomic force microscope (AFM) probes simultaneously, a novel oscillating probe based on a I2 shaped MEMS resonator was conceived, designed, fabricated and evaluated. To further improve the imaging capability of this kind of probe, structure design and measurement improvements were studied and presented in this work, including new detection scheme based on simple differential measurement and using locally doped piezoresistors at maximum strain locations. Experimental results showed that with these improvements, the feedthrough coupling effect between driving and sensing is effectively eliminated and the measurement sensitivity is improved by at least 10 times.
In order to effectively prompt the resonance frequency and the quality factor of atomic force microscope (AFM) probes simultaneously, a novel oscillating probe based on a I2 shaped MEMS resonator was conceived, designed, fabricated and evaluated. To further improve the imaging capability of this kind of probe, structure design and measurement improvements were studied and presented in this work, including new detection scheme based on simple differential measurement and using locally doped piezoresistors at maximum strain locations. Experimental results showed that with these improvements, the feedthrough coupling effect between driving and sensing is effectively eliminated and the measurement sensitivity is improved by at least 10 times.
2015,
27: 024120.
doi: 10.11884/HPLPB201527.024120
Abstract:
To improve the underwater acoustic detecting capability of DFB fiber laser, the optimization design and mechanism analysis of a sandwich-type encapsulated structure were carried out using FEA software ANSYS, by setting the relative acceleration sensitivity as objective function, the structural dimension parameters as design variables, and the structural first-order inherent frequency and sound pressure sensitivity of the probe as state variables. The analysis results show that when a 100 m unbalanced interferometer is used, the sound pressure sensitivity of the designed probe can achieves about -135.1 dB, and the relative acceleration sensitivity -19.6 dB. It is shown that by properly setting the thicknesses of the beams and arranging the connection joints, the DFB fiber laser hydrophone with the optimized encapsulated structure has high sound pressure sensitivity and improved anti-acceleration performance.
To improve the underwater acoustic detecting capability of DFB fiber laser, the optimization design and mechanism analysis of a sandwich-type encapsulated structure were carried out using FEA software ANSYS, by setting the relative acceleration sensitivity as objective function, the structural dimension parameters as design variables, and the structural first-order inherent frequency and sound pressure sensitivity of the probe as state variables. The analysis results show that when a 100 m unbalanced interferometer is used, the sound pressure sensitivity of the designed probe can achieves about -135.1 dB, and the relative acceleration sensitivity -19.6 dB. It is shown that by properly setting the thicknesses of the beams and arranging the connection joints, the DFB fiber laser hydrophone with the optimized encapsulated structure has high sound pressure sensitivity and improved anti-acceleration performance.
2015,
27: 024121.
doi: 10.11884/HPLPB201527.024121
Abstract:
Micro-ring resonator has been attracting attentions in studies of filters, modulators, lasers, sensors and other fields owing to the characteristics of highly integrated, low power consumption and high sensitivity. The transmission characteristics of micro-ring resonator directly determine the performance of micro-optical device for its key component of various integrated optical devices. The causes of and influences on resonant spectrum of ripple noise were analyzed by the combination of micro-ring resonator theory and Fabry-Perot Interferometer (FPI). Coupling experiments were designed to obtain and analyze the free spectrum range (FSR) and amplitude of ripple noise. The experimental results show that coupling gratings are the cause of ripple noise, which is well consistent with theoretical analysis. The relationship between etching depth of coupling gratings and ripple amplitude was found and analyzed. The study provides a reference for further optimization of micro-ring resonator and error analysis of micro-ring resonator system.
Micro-ring resonator has been attracting attentions in studies of filters, modulators, lasers, sensors and other fields owing to the characteristics of highly integrated, low power consumption and high sensitivity. The transmission characteristics of micro-ring resonator directly determine the performance of micro-optical device for its key component of various integrated optical devices. The causes of and influences on resonant spectrum of ripple noise were analyzed by the combination of micro-ring resonator theory and Fabry-Perot Interferometer (FPI). Coupling experiments were designed to obtain and analyze the free spectrum range (FSR) and amplitude of ripple noise. The experimental results show that coupling gratings are the cause of ripple noise, which is well consistent with theoretical analysis. The relationship between etching depth of coupling gratings and ripple amplitude was found and analyzed. The study provides a reference for further optimization of micro-ring resonator and error analysis of micro-ring resonator system.
2015,
27: 024122.
doi: 10.11884/HPLPB201527.024122
Abstract:
Nitrate(NO-3) is widely distributed in the water environment, and induces many problems. A platinum inter-digitated array (IDA) microelectrode modified with copper clusters has been developed to enhance the performance of the electrochemical sensor for nitrate determination. The IDA microelectrode was fabricated by Micro Electro-Mechanical System (MEMS) technique. The copper clusters electrodeposited on the IDA microelectrode are porous and have large surface area. The electrochemical performance of the modified microelectrode for nitrate determination was characterized by using linear sweep voltammetry in three-electrode system. The linear range of the copper modified IDA microelectrode for nitrate (N-NO-3) determination was from 0 to 2 mg/L with a linearity of 0.999 and a sensitivity of -3.15 ALmg-1. The IDA microelectrode with sensitive area of 1 mm2 possessed a higher electrocatalytic activity and superior sensitivity for nitrate determination than the disk microelectrode with indentical area due to the structure and edge effect of IDA microelectrode.
Nitrate(NO-3) is widely distributed in the water environment, and induces many problems. A platinum inter-digitated array (IDA) microelectrode modified with copper clusters has been developed to enhance the performance of the electrochemical sensor for nitrate determination. The IDA microelectrode was fabricated by Micro Electro-Mechanical System (MEMS) technique. The copper clusters electrodeposited on the IDA microelectrode are porous and have large surface area. The electrochemical performance of the modified microelectrode for nitrate determination was characterized by using linear sweep voltammetry in three-electrode system. The linear range of the copper modified IDA microelectrode for nitrate (N-NO-3) determination was from 0 to 2 mg/L with a linearity of 0.999 and a sensitivity of -3.15 ALmg-1. The IDA microelectrode with sensitive area of 1 mm2 possessed a higher electrocatalytic activity and superior sensitivity for nitrate determination than the disk microelectrode with indentical area due to the structure and edge effect of IDA microelectrode.
2015,
27: 024123.
doi: 10.11884/HPLPB201527.024123
Abstract:
A novel nano-grating coupler based on silicon-on-insulator structure is proposed to solve the mismatch issue between the silicon-based optical waveguide and the single-mode fiber. According to the principle of collimation, the structure model and characteristics of the nano-grating coupler are investigated by using the finite-difference time-domain method. Optiwave OptiFDTD 8.0 software is used to investigate the factors related to the coupling efficiency, such as the incident wavelength, the incident angle, the grating cycle, the grating duty ratio, the etching depth, the buried-oxide layer thickness and so on. Optimum parameters of the grating structure are obtained. The structure is optimized by adding the rear reflector, the antireflective film and the bottom dielectric reflector on the base of the basic grating. The maximum coupling efficiency of the grating coupler is up to 59.37% with a 3 dB bandwidth of 65 nm.
A novel nano-grating coupler based on silicon-on-insulator structure is proposed to solve the mismatch issue between the silicon-based optical waveguide and the single-mode fiber. According to the principle of collimation, the structure model and characteristics of the nano-grating coupler are investigated by using the finite-difference time-domain method. Optiwave OptiFDTD 8.0 software is used to investigate the factors related to the coupling efficiency, such as the incident wavelength, the incident angle, the grating cycle, the grating duty ratio, the etching depth, the buried-oxide layer thickness and so on. Optimum parameters of the grating structure are obtained. The structure is optimized by adding the rear reflector, the antireflective film and the bottom dielectric reflector on the base of the basic grating. The maximum coupling efficiency of the grating coupler is up to 59.37% with a 3 dB bandwidth of 65 nm.
2015,
27: 024124.
doi: 10.11884/HPLPB201527.024124
Abstract:
The concentration of most environmental samples is very low. In order to directly detect these samples, an integrated micro pre-concentrator, which can significantly improve detection limit of mini gas chromatography system with 1-2 orders, is developed. The micro pre-concentrator has 4 parallel channels filled with enough Tenax-TA as adsorbent materials for concentrating volatile organic compounds. For closing the released components during thermal desorption process, a micro-valve is integrated behind the pre-concentrator. The result demonstrates the proposed pre-concentrator can effectively concentrate components with a concentration factor of 15. Moreover, the chromatography peak broadening is greatly compressed under controlling by the micro-valve. Therefore, the micro-fabricated pre-concentrator can be easy to deploy and suitable for a number of applications involving on-site monitoring of environmental samples.
The concentration of most environmental samples is very low. In order to directly detect these samples, an integrated micro pre-concentrator, which can significantly improve detection limit of mini gas chromatography system with 1-2 orders, is developed. The micro pre-concentrator has 4 parallel channels filled with enough Tenax-TA as adsorbent materials for concentrating volatile organic compounds. For closing the released components during thermal desorption process, a micro-valve is integrated behind the pre-concentrator. The result demonstrates the proposed pre-concentrator can effectively concentrate components with a concentration factor of 15. Moreover, the chromatography peak broadening is greatly compressed under controlling by the micro-valve. Therefore, the micro-fabricated pre-concentrator can be easy to deploy and suitable for a number of applications involving on-site monitoring of environmental samples.
2015,
27: 024125.
doi: 10.11884/HPLPB201527.024125
Abstract:
The MEMS bionic vector hydrophone, which has advantages of high sensitivity, broad frequency band, vector and high Signal to Noise Ratio(SNR), is one kind of underwater acoustic signal detection device integrating piezoelectricity and MEMS technology. However, to make a further step in improving the predictive accuracy and the resonant frequency of underwater acoustic signal, optimization design of the MEMS hydrophone bionic microstructure is performed with finite element method in this paper. Firstly, it can be learned from theoretical formulas of natural frequency and stress that the natural frequency of bionic microstructure is inversely-proportional to the height of bionic cilia and the beam length, at the same time, is proportional to the beam width and thickness; Instead, the sensitivity is proportional to the bionic cilia height and beam length, and is inversely-proportional to the beam width and thickness. Based on the theoretical analysis, maximum stress curves and resonance frequency curves of sensor under different structural parameters are drawn. Secondly, a static analysis was done with ANSYS software and a response curve of natural frequency and stress was drawn. Finally, the simulation results show that a better performance of high sensitivity and broad frequency band for MEMS hydrophones can be obtained by designing beam length, width, thickness and bionic cilia height and radius as 400, 80, 50, 1000 and 80 m respectively. The simulation results and the theoretical analysis are compared, and the differences between them are analyzed.
The MEMS bionic vector hydrophone, which has advantages of high sensitivity, broad frequency band, vector and high Signal to Noise Ratio(SNR), is one kind of underwater acoustic signal detection device integrating piezoelectricity and MEMS technology. However, to make a further step in improving the predictive accuracy and the resonant frequency of underwater acoustic signal, optimization design of the MEMS hydrophone bionic microstructure is performed with finite element method in this paper. Firstly, it can be learned from theoretical formulas of natural frequency and stress that the natural frequency of bionic microstructure is inversely-proportional to the height of bionic cilia and the beam length, at the same time, is proportional to the beam width and thickness; Instead, the sensitivity is proportional to the bionic cilia height and beam length, and is inversely-proportional to the beam width and thickness. Based on the theoretical analysis, maximum stress curves and resonance frequency curves of sensor under different structural parameters are drawn. Secondly, a static analysis was done with ANSYS software and a response curve of natural frequency and stress was drawn. Finally, the simulation results show that a better performance of high sensitivity and broad frequency band for MEMS hydrophones can be obtained by designing beam length, width, thickness and bionic cilia height and radius as 400, 80, 50, 1000 and 80 m respectively. The simulation results and the theoretical analysis are compared, and the differences between them are analyzed.
2015,
27: 024126.
doi: 10.11884/HPLPB201527.024126
Abstract:
A novel hybrid resonator structure is fabricated by coating low refractive index ultraviolet glue to the surface of microsphere resonator. By analyzing the thermal optical coefficient in such structure, the thermal nonlinear effect is demonstrated theoretically and experimentally and the experimental results show that a larger thermal nonlinear coefficient can be achieved. Simultaneously, it is verified that quality factor has influenced the thermal nonlinear coefficient. This work presents that the hybrid resonator structure could be used to improve the thermal nonlinear effect for applications in thermal sensors and the sensitivity can be increased at 2.8 times.
A novel hybrid resonator structure is fabricated by coating low refractive index ultraviolet glue to the surface of microsphere resonator. By analyzing the thermal optical coefficient in such structure, the thermal nonlinear effect is demonstrated theoretically and experimentally and the experimental results show that a larger thermal nonlinear coefficient can be achieved. Simultaneously, it is verified that quality factor has influenced the thermal nonlinear coefficient. This work presents that the hybrid resonator structure could be used to improve the thermal nonlinear effect for applications in thermal sensors and the sensitivity can be increased at 2.8 times.
2015,
27: 024127.
doi: 10.11884/HPLPB201527.024127
Abstract:
An electrostatically actuated microelectromechanical systems (MEMS) tilting mirror based on self-assembly is proposed and fabricated using the poly multi-user MEMS process (PolyMUMPs). The tilting mirror is composed of one central mirror, two torsional springs and two bimorph suspension beams for self-assembly. The central mirror can be lifted off the substrate due to residual stresses in Au-polysilicon bimorph suspension beams. Thermal anneal technique is employed to increase the residual stress in Au film. The structure is optimized by Finite Element Analysis (FEA) and experimentally verified. The torsion angle of the tilting mirror gets to 3.6 with 200 C thermal anneal. The tilting mirror has potential to be implemented formirco-opto-electro-mechanical systems (MOEMS).
An electrostatically actuated microelectromechanical systems (MEMS) tilting mirror based on self-assembly is proposed and fabricated using the poly multi-user MEMS process (PolyMUMPs). The tilting mirror is composed of one central mirror, two torsional springs and two bimorph suspension beams for self-assembly. The central mirror can be lifted off the substrate due to residual stresses in Au-polysilicon bimorph suspension beams. Thermal anneal technique is employed to increase the residual stress in Au film. The structure is optimized by Finite Element Analysis (FEA) and experimentally verified. The torsion angle of the tilting mirror gets to 3.6 with 200 C thermal anneal. The tilting mirror has potential to be implemented formirco-opto-electro-mechanical systems (MOEMS).
2015,
27: 024128.
doi: 10.11884/HPLPB201527.024128
Abstract:
In order to overcome the deficiency in the fabrication of triangular prism slit (TPS) electrode pairs with ultrathick and high aspect ratio, to obtain a jet generator with good appearance and in that way improve the output performance of electro-conjugate fluid (ECF) micropump, several optimization measures for the fabrication of TPS electrode pairs based on MEMS technology are proposed. By repeating experiment and improvement based on theoretical analysis, structural optimization of slit electrode, optimized process parameter for spin coating, heat treatment, development and a novel removal method for KMPR negative photoresists are utilized. Finally, the jet generator with thickness of almost 500 m and high aspect ratio of TPS electrode pairs are fabricated successfully. The tip of triangular prism electrode has unbroken structure and the slit electrode attaches to the conductor layer well. Moreover, a prototype of ECF micropump is designed and assembled for next experimental study.
In order to overcome the deficiency in the fabrication of triangular prism slit (TPS) electrode pairs with ultrathick and high aspect ratio, to obtain a jet generator with good appearance and in that way improve the output performance of electro-conjugate fluid (ECF) micropump, several optimization measures for the fabrication of TPS electrode pairs based on MEMS technology are proposed. By repeating experiment and improvement based on theoretical analysis, structural optimization of slit electrode, optimized process parameter for spin coating, heat treatment, development and a novel removal method for KMPR negative photoresists are utilized. Finally, the jet generator with thickness of almost 500 m and high aspect ratio of TPS electrode pairs are fabricated successfully. The tip of triangular prism electrode has unbroken structure and the slit electrode attaches to the conductor layer well. Moreover, a prototype of ECF micropump is designed and assembled for next experimental study.
2015,
27: 024129.
doi: 10.11884/HPLPB201527.024129
Abstract:
A MEMS patch antenna which can be integrated with RF module easily was designed to improve the bandwidth and gain of the traditional microstrip antenna. The equivalent dielectric constant of substrate of the microstrip antenna was optimized to greatly increase the bandwidth of the antenna by a high resistivity silicon being bonded to a low resistivity silicon to form a double-layer silicon substrate under the MEMS technology. Defected ground structure was also used on ground plane in order to restrain the harmonic radiation of antenna. Based on the above aspects, a 22 antenna array was designed with a center frequency of 10 GHz. The simulation results show that the antenna array has an impendence bandwidth of 15.9% and a gain of 10.9 dB, significantly better than traditional antennas and meets the anti-interference requirements of antennas in the fuze.
A MEMS patch antenna which can be integrated with RF module easily was designed to improve the bandwidth and gain of the traditional microstrip antenna. The equivalent dielectric constant of substrate of the microstrip antenna was optimized to greatly increase the bandwidth of the antenna by a high resistivity silicon being bonded to a low resistivity silicon to form a double-layer silicon substrate under the MEMS technology. Defected ground structure was also used on ground plane in order to restrain the harmonic radiation of antenna. Based on the above aspects, a 22 antenna array was designed with a center frequency of 10 GHz. The simulation results show that the antenna array has an impendence bandwidth of 15.9% and a gain of 10.9 dB, significantly better than traditional antennas and meets the anti-interference requirements of antennas in the fuze.
2015,
27: 024130.
doi: 10.11884/HPLPB201527.024130
Abstract:
Chip-scale atomic clock (CSAC) mainly includes an RF source, a physics package and other peripheral control circuits. The RF source which is related to the short-term stability of the CSAC plays an important role in CSACs. The technology of digital phase-locked loop is used to realize the 4.596 GHz RF source in this paper. The RF source is made up of three parts, including the fractional-N frequency synthesizer chip, the voltage-controlled oscillator (VCO) and the loop filter. Advantages of digital phase-locked loop used in the microwave signal source are low phase noise and pure spectrum. Furthermore, as the fractional-N frequency synthesizer chip is programmable, the output frequency can be swept by configuring the values of R divider and N divider, making the frequency control of CSACs easy. With the related formula, parameters of the loop filter are calculated approximately, and a loop filter with 300 kHz loop bandwidth and 55 phase margin is designed. Finally, The whole RF source based on the digital phase-locked loop is simulated, fabricated and tested. The result shows that the phase noise of the RF source is -74.02 dBc/Hz at 300 Hz offset, which meets the requirement of the RF source for CSACs.
Chip-scale atomic clock (CSAC) mainly includes an RF source, a physics package and other peripheral control circuits. The RF source which is related to the short-term stability of the CSAC plays an important role in CSACs. The technology of digital phase-locked loop is used to realize the 4.596 GHz RF source in this paper. The RF source is made up of three parts, including the fractional-N frequency synthesizer chip, the voltage-controlled oscillator (VCO) and the loop filter. Advantages of digital phase-locked loop used in the microwave signal source are low phase noise and pure spectrum. Furthermore, as the fractional-N frequency synthesizer chip is programmable, the output frequency can be swept by configuring the values of R divider and N divider, making the frequency control of CSACs easy. With the related formula, parameters of the loop filter are calculated approximately, and a loop filter with 300 kHz loop bandwidth and 55 phase margin is designed. Finally, The whole RF source based on the digital phase-locked loop is simulated, fabricated and tested. The result shows that the phase noise of the RF source is -74.02 dBc/Hz at 300 Hz offset, which meets the requirement of the RF source for CSACs.
2015,
27: 024131.
doi: 10.11884/HPLPB201527.024131
Abstract:
The superlens nanolithography is a promising technique for patterning nanoscale structures because of its ability to overcome the diffraction limit. Until 2005, Zhang and his co-works successfully obtained images such as line grating and NANOalphabet through a thin silver film with a UV light at 365 nm wavelength and the resolution is down to 1/6 of the incidence wavelength. In this paper, subwavelength imaging of periodic and isolated nanostructures through a new silver superlens is investigated by appropriately choosing the material and designing the thickness of each layer in the lens structure as well as controlling the experimental procedure. The superlens structure was optimized by means of the transfer transmission matrix method. Subwavelenght imaging of periodic and isolated nanostructures was performed through this superlens structure. The experiments show that for periodic nanostructures the imaging resolution is about 100 nm, while for isolated nanostructues the resolution is below 50 nm, less than 1/7 of the incidence wavelength.
The superlens nanolithography is a promising technique for patterning nanoscale structures because of its ability to overcome the diffraction limit. Until 2005, Zhang and his co-works successfully obtained images such as line grating and NANOalphabet through a thin silver film with a UV light at 365 nm wavelength and the resolution is down to 1/6 of the incidence wavelength. In this paper, subwavelength imaging of periodic and isolated nanostructures through a new silver superlens is investigated by appropriately choosing the material and designing the thickness of each layer in the lens structure as well as controlling the experimental procedure. The superlens structure was optimized by means of the transfer transmission matrix method. Subwavelenght imaging of periodic and isolated nanostructures was performed through this superlens structure. The experiments show that for periodic nanostructures the imaging resolution is about 100 nm, while for isolated nanostructues the resolution is below 50 nm, less than 1/7 of the incidence wavelength.
2015,
27: 024132.
doi: 10.11884/HPLPB201527.024132
Abstract:
Insertion loss is an important performance indicator for radio frequency micro-electro-mechanical systems (RF MEMS) switches. The RF MEMS capacitive switch is a kind of RF MEMS switch which is suitable for high frequency use. Its loss mechanisms are investigated in this paper. Four main parts contribute to the RF MEMS capacitive switchs insertion loss: conductor loss of the signal lines, substrate loss, radiation loss, and MEMS bridge loss. Loss models are built and calculated, and numerical calculation results agree well with simulation results. In addition, influence factors of insertion loss are analyzed, and results show that high resistivity substrate, conductor width around 200 m, smaller conductor thickness and smaller up-state capacitance can help lower the insertion loss.
Insertion loss is an important performance indicator for radio frequency micro-electro-mechanical systems (RF MEMS) switches. The RF MEMS capacitive switch is a kind of RF MEMS switch which is suitable for high frequency use. Its loss mechanisms are investigated in this paper. Four main parts contribute to the RF MEMS capacitive switchs insertion loss: conductor loss of the signal lines, substrate loss, radiation loss, and MEMS bridge loss. Loss models are built and calculated, and numerical calculation results agree well with simulation results. In addition, influence factors of insertion loss are analyzed, and results show that high resistivity substrate, conductor width around 200 m, smaller conductor thickness and smaller up-state capacitance can help lower the insertion loss.
2015,
27: 024133.
doi: 10.11884/HPLPB201527.024133
Abstract:
ZnO/Au films were deposited on oxidized silicon substrate by RF reactive sputtering technique and treated under various post-annealing atmospheres. X-ray diffraction (XRD), optical microscopy, field emission scanning electron microscope (FESEM) and piezometer were employed to analyze the effect of post-annealing on the structure and piezoelectric properties of ZnO/Au thin films. Crystalline qualities of ZnO/Au films were improved by post-annealing especially after careful annealing in nitrogen atmosphere. But piezoelectric parameters d33 and d15 decreased after having annealed. The Au atomic migration under high annealing temperature was considered as the reason that exacerbated the piezoelectric properties of ZnO/Au films.
ZnO/Au films were deposited on oxidized silicon substrate by RF reactive sputtering technique and treated under various post-annealing atmospheres. X-ray diffraction (XRD), optical microscopy, field emission scanning electron microscope (FESEM) and piezometer were employed to analyze the effect of post-annealing on the structure and piezoelectric properties of ZnO/Au thin films. Crystalline qualities of ZnO/Au films were improved by post-annealing especially after careful annealing in nitrogen atmosphere. But piezoelectric parameters d33 and d15 decreased after having annealed. The Au atomic migration under high annealing temperature was considered as the reason that exacerbated the piezoelectric properties of ZnO/Au films.
2015,
27: 024134.
doi: 10.11884/HPLPB201527.024134
Abstract:
In this work, hydrogenated amorphous silicon thin film transistors (-Si:H TFTs) with the 98 nm thick nano -Si:H thin film and the channel aspect ratio 10 m/40 m are demonstrated, which are based on silicon-on-insulator (SOI) materials and fabricated by RF-PECVD system. The methods, SEM, XRD as well as Raman spectra, are employed to characterize the morphologic and structural properties of the nano -Si:H thin film at different annealing temperatures. CMOS processing, anisotropic etching solution EPW, radio frequency spurting and plasma etching techniques are adopted to fabricate -Si:H TFTs together with IDS-VDS characteristics. Besides ubiquitous characteristics of -Si:H TFTs, the simulation model, allowing for energy balance transport mechanism, is established to specially investigate negative resistance phenomena occurred during experiments. The results from the extraction of the energy band diagram at the interface between the nano -Si:H thin film and gate oxide indicate that the valence band energy decreases with the drain voltage ascending from 6 V to 30 V adjacent to the drain within 0.5 m. All these demonstrate that the fallen voltage close to the drain within 0.5 m is responsible for the negative resistance characteristics.
In this work, hydrogenated amorphous silicon thin film transistors (-Si:H TFTs) with the 98 nm thick nano -Si:H thin film and the channel aspect ratio 10 m/40 m are demonstrated, which are based on silicon-on-insulator (SOI) materials and fabricated by RF-PECVD system. The methods, SEM, XRD as well as Raman spectra, are employed to characterize the morphologic and structural properties of the nano -Si:H thin film at different annealing temperatures. CMOS processing, anisotropic etching solution EPW, radio frequency spurting and plasma etching techniques are adopted to fabricate -Si:H TFTs together with IDS-VDS characteristics. Besides ubiquitous characteristics of -Si:H TFTs, the simulation model, allowing for energy balance transport mechanism, is established to specially investigate negative resistance phenomena occurred during experiments. The results from the extraction of the energy band diagram at the interface between the nano -Si:H thin film and gate oxide indicate that the valence band energy decreases with the drain voltage ascending from 6 V to 30 V adjacent to the drain within 0.5 m. All these demonstrate that the fallen voltage close to the drain within 0.5 m is responsible for the negative resistance characteristics.
2015,
27: 024135.
doi: 10.11884/HPLPB201527.024135
Abstract:
Nano-crystalline LaNiAl film charged with helium atoms is prepared by magnetron co-sputtering. Low energy helium-4 atoms implantation is carried out by magnetron co-sputtering technique with Ar/He mixture gases around during the film growth. During the sputtering process, the ionized He atoms bombarding the cathode target are backscattered and implanted into the growing film. The film is CaCu5-type structure analyzed by XRD. Helium concentration is measured by proton backscattering spectroscopy (PBS), the most atom fraction of helium is 12.2%. Deduced by thermal desorption experiments and TEM, helium exists as He-V cluster in the nano-crystal films. Compared with 3He in a tritide, the implanted He in metal film is still quite different, but it is a good way to study how helium atom exists in La-Ni-Al inter-metallic compound.
Nano-crystalline LaNiAl film charged with helium atoms is prepared by magnetron co-sputtering. Low energy helium-4 atoms implantation is carried out by magnetron co-sputtering technique with Ar/He mixture gases around during the film growth. During the sputtering process, the ionized He atoms bombarding the cathode target are backscattered and implanted into the growing film. The film is CaCu5-type structure analyzed by XRD. Helium concentration is measured by proton backscattering spectroscopy (PBS), the most atom fraction of helium is 12.2%. Deduced by thermal desorption experiments and TEM, helium exists as He-V cluster in the nano-crystal films. Compared with 3He in a tritide, the implanted He in metal film is still quite different, but it is a good way to study how helium atom exists in La-Ni-Al inter-metallic compound.
2015,
27: 024136.
doi: 10.11884/HPLPB201527.024136
Abstract:
The equipment of liquid electro-deposition for diamond-like carbon (DLC) films was set up. DLC films were deposited on stainless steel and Si substrates by electrolysis in a methanol solution with a pulse-direct current power supply. The morphology and microstructure of the deposited DLC films were analyzed using scanning electron microscopy (SEM) and Raman spectroscopy. Friction and wear properties of the films were tested by the UMT-2M friction-wear tester of CETR Corporation. The experimental results show that DLC films are smooth and compact. Raman spectroscopy analysis confirmed the presence of a strong peak at 1332 cm-1, which is assigned to crystalline diamond. The content of sp3 for the stainless steel substrate is higher than that for the Si substrates. At ambient conditions, the friction coefficient of DLC films on stainless steel substrates is 0.12, and the friction coefficient of DLC films on Si substrates is 0.10. The wear-resistant property of DLC films on stainless steel substrates is more excellent than that of DLC films on Si substrates.
The equipment of liquid electro-deposition for diamond-like carbon (DLC) films was set up. DLC films were deposited on stainless steel and Si substrates by electrolysis in a methanol solution with a pulse-direct current power supply. The morphology and microstructure of the deposited DLC films were analyzed using scanning electron microscopy (SEM) and Raman spectroscopy. Friction and wear properties of the films were tested by the UMT-2M friction-wear tester of CETR Corporation. The experimental results show that DLC films are smooth and compact. Raman spectroscopy analysis confirmed the presence of a strong peak at 1332 cm-1, which is assigned to crystalline diamond. The content of sp3 for the stainless steel substrate is higher than that for the Si substrates. At ambient conditions, the friction coefficient of DLC films on stainless steel substrates is 0.12, and the friction coefficient of DLC films on Si substrates is 0.10. The wear-resistant property of DLC films on stainless steel substrates is more excellent than that of DLC films on Si substrates.
2015,
27: 024137.
doi: 10.11884/HPLPB201527.024137
Abstract:
Nanocrystalline diamond films depict superior tribological properties indicated from low friction coefficient and high wear resistance. The system pressure is one of the important processing parameters to prepare nanocrystalline diamond films. In this paper, diamond films were deposited at different pressures, and the sample was analyzed by scanning electron microscopy(SEM) and Raman spectrum. By the hot-filament chemical vapor deposition technique, when the methane was superfluous, the nanocrystalline diamond films could be deposited at right pressure. Higher system pressure would hamper the nuclei and the growth of nanodiamond films, and lower system pressure would cause diamond films grains coarse. The mechanism by which system pressures have the effect on the growth of diamond films is that the movement of atom H changes at different pressure.
Nanocrystalline diamond films depict superior tribological properties indicated from low friction coefficient and high wear resistance. The system pressure is one of the important processing parameters to prepare nanocrystalline diamond films. In this paper, diamond films were deposited at different pressures, and the sample was analyzed by scanning electron microscopy(SEM) and Raman spectrum. By the hot-filament chemical vapor deposition technique, when the methane was superfluous, the nanocrystalline diamond films could be deposited at right pressure. Higher system pressure would hamper the nuclei and the growth of nanodiamond films, and lower system pressure would cause diamond films grains coarse. The mechanism by which system pressures have the effect on the growth of diamond films is that the movement of atom H changes at different pressure.
2015,
27: 024138.
doi: 10.11884/HPLPB201527.024138
Abstract:
In order to obtain the high-fidelity model of self-actuation failure threshold power of the capacitive RF MEMS switch, it is necessary to clear the fringing field effect of the electric field distribution on switch membrane. The area of the switch membrane subjected to RF signal power (ARF) cant be replaced with the switch area over the center conductor (A) in the calculation of expression of self-actuation failure threshold power (Pact) of the switch, because of the influence of the fringing field effect. Otherwise, the deviation of calculation will occur in the RF signal power equivalent voltage (Veq). Therefore, ARF is characterized by using the ratio between the calculated Veq and the Root-Mean-Square voltage (VRMS) of the switch membrane. And ARF/A, a figure of merit (FoM), is constructed to characterize the intensity of the fringing field effect of the electric field distribution on the membrane. The 3D electromagnetic model of self-actuation failure of the switch is constructed using the HFSS (High Frequency Structure Simulator) code. Through the simulation, the distribution of fringing electric field on the membrane in variety of RF signal power (Pin) and air gap of the switch (g0) for the case of a common configuration of the switch is obtained. By comparing the calculation value of FoM and simulation results, the feasibility of using ARF/A, the FoM, to characterize the intensity of the fringing field effect of the electric field distribution on the membrane is preliminarily validated.
In order to obtain the high-fidelity model of self-actuation failure threshold power of the capacitive RF MEMS switch, it is necessary to clear the fringing field effect of the electric field distribution on switch membrane. The area of the switch membrane subjected to RF signal power (ARF) cant be replaced with the switch area over the center conductor (A) in the calculation of expression of self-actuation failure threshold power (Pact) of the switch, because of the influence of the fringing field effect. Otherwise, the deviation of calculation will occur in the RF signal power equivalent voltage (Veq). Therefore, ARF is characterized by using the ratio between the calculated Veq and the Root-Mean-Square voltage (VRMS) of the switch membrane. And ARF/A, a figure of merit (FoM), is constructed to characterize the intensity of the fringing field effect of the electric field distribution on the membrane. The 3D electromagnetic model of self-actuation failure of the switch is constructed using the HFSS (High Frequency Structure Simulator) code. Through the simulation, the distribution of fringing electric field on the membrane in variety of RF signal power (Pin) and air gap of the switch (g0) for the case of a common configuration of the switch is obtained. By comparing the calculation value of FoM and simulation results, the feasibility of using ARF/A, the FoM, to characterize the intensity of the fringing field effect of the electric field distribution on the membrane is preliminarily validated.
2015,
27: 024139.
doi: 10.11884/HPLPB201527.024139
Abstract:
The multi-layer graphene, thickness being 10-180 nm, was prepared by the method of liquid ultrasonic stripping in deionized water, n-butanol, dimethyl sulfoxide and characterized by transmission electron microscope (TEM) and atomic force microscope (AFM). The tribological properties of multi-layer graphene as lubricant additive were investigated using a multi-functional reciprocating friction and wear tester. By the addition of multi-layer graphene in paraffin liquid, the friction coefficient was decreased and the antiwear ability was improved. It is concluded that the formation of physisorption films and tribochemistry reaction films on the worn surface can explain the excellent friction and wear properties of multi-layer graphene.
The multi-layer graphene, thickness being 10-180 nm, was prepared by the method of liquid ultrasonic stripping in deionized water, n-butanol, dimethyl sulfoxide and characterized by transmission electron microscope (TEM) and atomic force microscope (AFM). The tribological properties of multi-layer graphene as lubricant additive were investigated using a multi-functional reciprocating friction and wear tester. By the addition of multi-layer graphene in paraffin liquid, the friction coefficient was decreased and the antiwear ability was improved. It is concluded that the formation of physisorption films and tribochemistry reaction films on the worn surface can explain the excellent friction and wear properties of multi-layer graphene.
2015,
27: 024140.
doi: 10.11884/HPLPB201527.024140
Abstract:
Carbon-incorporated octahedral Co3O4 was synthesized via a novel and environment-friendly one-pot method using degreasing cotton as the sacrificial templates and its photocatalytic ability on producing H2 from water/ethanol solution under simulated solar light condition was investigated. X-ray diffraction (XRD) and scanning electron microscope (SEM) were performed to characterize the structure and morphology of the octahedral Co3O4 with a particle size of about 10 um. The energy dispersive spectrometer (EDS) manifested the incorporation of carbon species into octahedral Co3O4 and the X-ray photoelectron spectroscopy (XPS) confirmed that the carbon species come from the incomplete combustion of the degreasing cotton. The probable formation procedure of the carbon-incorporated octahedral Co3O4 was proposed. Notably, the resultant Co3O4 exhibited a promising capability on splitting water into H2.
Carbon-incorporated octahedral Co3O4 was synthesized via a novel and environment-friendly one-pot method using degreasing cotton as the sacrificial templates and its photocatalytic ability on producing H2 from water/ethanol solution under simulated solar light condition was investigated. X-ray diffraction (XRD) and scanning electron microscope (SEM) were performed to characterize the structure and morphology of the octahedral Co3O4 with a particle size of about 10 um. The energy dispersive spectrometer (EDS) manifested the incorporation of carbon species into octahedral Co3O4 and the X-ray photoelectron spectroscopy (XPS) confirmed that the carbon species come from the incomplete combustion of the degreasing cotton. The probable formation procedure of the carbon-incorporated octahedral Co3O4 was proposed. Notably, the resultant Co3O4 exhibited a promising capability on splitting water into H2.
2015,
27: 024141.
doi: 10.11884/HPLPB201527.024141
Abstract:
Organic semiconductor nanoparticles composed of fullerene C60 and/or metal-free phthalocyanine (denoted as Pc) were synthesized by a reprecipitation method, in which N-methyl-2-pyrrolidone (NMP) solutions dissolving C60 and/or Pc were injected into another solvent (e.g., water or ethanol, denoted as poor solvent). The - interaction between C60 and Pc molecules in the mixed NMP solution was confirmed as observing charge-transfer absorption band in the absorption spectrum. Therefore, it is presumed that the prepared composite nanoparticles consist of donor-acceptor (D-A) structure, which is in accordance with the X-ray diffraction result. The nanocomposites average size and morphology can be controlled by using different poor solvents or varying volume ratio of the NMP solutions to the poor solvent. Moreover, the obtained nanoparticles combined with Nafion were used as photocatalysts to remove trimethylamine (TMA). The sample containing the nanocomposites showed better activity to remove TMA than that containing only C60 or Pc nanoparticles under visible light, indicating that D-A structure is helpful to enhance the photocatalytic activity of the nanoparticles. The present research demonstrated a novel organic photocatalyst featuring D-A structure.
Organic semiconductor nanoparticles composed of fullerene C60 and/or metal-free phthalocyanine (denoted as Pc) were synthesized by a reprecipitation method, in which N-methyl-2-pyrrolidone (NMP) solutions dissolving C60 and/or Pc were injected into another solvent (e.g., water or ethanol, denoted as poor solvent). The - interaction between C60 and Pc molecules in the mixed NMP solution was confirmed as observing charge-transfer absorption band in the absorption spectrum. Therefore, it is presumed that the prepared composite nanoparticles consist of donor-acceptor (D-A) structure, which is in accordance with the X-ray diffraction result. The nanocomposites average size and morphology can be controlled by using different poor solvents or varying volume ratio of the NMP solutions to the poor solvent. Moreover, the obtained nanoparticles combined with Nafion were used as photocatalysts to remove trimethylamine (TMA). The sample containing the nanocomposites showed better activity to remove TMA than that containing only C60 or Pc nanoparticles under visible light, indicating that D-A structure is helpful to enhance the photocatalytic activity of the nanoparticles. The present research demonstrated a novel organic photocatalyst featuring D-A structure.
2015,
27: 024142.
doi: 10.11884/HPLPB201527.024142
Abstract:
TiO2 nanotube arrays were fabricated by anodic oxidation of titanium foil in ethylene glycol electrolytes with different amount of water. The influences of water content on the conductivity, viscosity and current were studied by the curve of conductivity, viscosity and the loop current recorded online in the reaction process changing with time. The relationship between the dimension and the quantity of electric charge consumption of chemical dissolution of TiO2 oxide films was analyzed. The results show that cubics function relationship existed between viscosity and water content and between conductivity and water content. The correlation coefficients were 0.992 5 and 0.977 8, respectively. Viscosity of electrolyte increased slowly in the reaction process. Viscosity of electrolyte with different water content was not similar. Diversities in the number of H+ and OH- of electrolyte, as well as different transfer rate of F- resulted in the variation trends of current-time curve and conductivity-time curve. When the water content was 4%, 5%, 6% and 10%, the nanotubes morphology was highly in order and there was little debris on the surface of the TiO2 nanotube arrays. The nanotubes diameter was between 50 nm and 72 nm, and the length ranged from 850 nm to 1.90 m. The quantity of electric charge consumption of chemical dissolution of TiO2 oxide films in line with volume of TiO2 films dissolved in the electrolyte, the volume of TiO2 films dissolved increased with the increasing of the quantity of electric charge consumption of chemical dissolution of TiO2 oxide films, which provided a theoretical basis for the preparation of morphology and dimension controllable nanotube arrays.
TiO2 nanotube arrays were fabricated by anodic oxidation of titanium foil in ethylene glycol electrolytes with different amount of water. The influences of water content on the conductivity, viscosity and current were studied by the curve of conductivity, viscosity and the loop current recorded online in the reaction process changing with time. The relationship between the dimension and the quantity of electric charge consumption of chemical dissolution of TiO2 oxide films was analyzed. The results show that cubics function relationship existed between viscosity and water content and between conductivity and water content. The correlation coefficients were 0.992 5 and 0.977 8, respectively. Viscosity of electrolyte increased slowly in the reaction process. Viscosity of electrolyte with different water content was not similar. Diversities in the number of H+ and OH- of electrolyte, as well as different transfer rate of F- resulted in the variation trends of current-time curve and conductivity-time curve. When the water content was 4%, 5%, 6% and 10%, the nanotubes morphology was highly in order and there was little debris on the surface of the TiO2 nanotube arrays. The nanotubes diameter was between 50 nm and 72 nm, and the length ranged from 850 nm to 1.90 m. The quantity of electric charge consumption of chemical dissolution of TiO2 oxide films in line with volume of TiO2 films dissolved in the electrolyte, the volume of TiO2 films dissolved increased with the increasing of the quantity of electric charge consumption of chemical dissolution of TiO2 oxide films, which provided a theoretical basis for the preparation of morphology and dimension controllable nanotube arrays.
2015,
27: 024143.
doi: 10.11884/HPLPB201527.024143
Abstract:
Monocrystalline silicon (c-Si) surfaces were microstructured and hyperdoped in SF6 atmosphere using femtosecond(fs) Ti:sapphire and nanosecond(ns) Nd:yttrium-aluminum-garnet laser pulses, respectively, for photovoltaic applications. The obtained microstructures were studied with respect to surface morphology, crystallinity, concentration and distribution of sulfur impurities. The experimental results indicate that the ns-laser microstructured silicon has a lower sheet resistance, a lower defect density (i.e., higher crystallinity) and a higher concentration of sulfur impurities distribution over a larger surface area and depth (about 1 m). In addition, its absorbance can reach about 80% from the visible region to the near-infrared spectral region. With the better performance of ns-laser treated silicon, solar cells with an active area of 8 cm2 were manufactured on the samples. The series resistance, open-circuit voltage, short-circuit current density, and conversion efficiency of the best solar cell are 0.5 , 503 mV, 35 mA/cm2, and about 12%, respectively. And these can be further improved by manufacturing process optimization.
Monocrystalline silicon (c-Si) surfaces were microstructured and hyperdoped in SF6 atmosphere using femtosecond(fs) Ti:sapphire and nanosecond(ns) Nd:yttrium-aluminum-garnet laser pulses, respectively, for photovoltaic applications. The obtained microstructures were studied with respect to surface morphology, crystallinity, concentration and distribution of sulfur impurities. The experimental results indicate that the ns-laser microstructured silicon has a lower sheet resistance, a lower defect density (i.e., higher crystallinity) and a higher concentration of sulfur impurities distribution over a larger surface area and depth (about 1 m). In addition, its absorbance can reach about 80% from the visible region to the near-infrared spectral region. With the better performance of ns-laser treated silicon, solar cells with an active area of 8 cm2 were manufactured on the samples. The series resistance, open-circuit voltage, short-circuit current density, and conversion efficiency of the best solar cell are 0.5 , 503 mV, 35 mA/cm2, and about 12%, respectively. And these can be further improved by manufacturing process optimization.
2015,
27: 024144.
doi: 10.11884/HPLPB201527.024144
Abstract:
Amorphous powder/silicone rubber composite was prepared by blending amorphous Fe73.5Cu1Nb3Si13.5B9 magnetic nano-powder with silicone rubber. Impedance property of the obtained composite was studied by a home-made device. Scanning electron microscope was used to study the surface and scattering property of the amorphous particles. Other factors, such as the insulation of the composite, single or multi layered, addition of conductive layer and the number of conductive on the property of impedance were studied. The results indicate that addition of conductive copper layer is effective for the improvement of pressure-sensitive property. Composite film/copper film/composite film designed here is actually equivalent to polymer/metal/polymer structure, which could enhance the pressure sensitive property of the system.
Amorphous powder/silicone rubber composite was prepared by blending amorphous Fe73.5Cu1Nb3Si13.5B9 magnetic nano-powder with silicone rubber. Impedance property of the obtained composite was studied by a home-made device. Scanning electron microscope was used to study the surface and scattering property of the amorphous particles. Other factors, such as the insulation of the composite, single or multi layered, addition of conductive layer and the number of conductive on the property of impedance were studied. The results indicate that addition of conductive copper layer is effective for the improvement of pressure-sensitive property. Composite film/copper film/composite film designed here is actually equivalent to polymer/metal/polymer structure, which could enhance the pressure sensitive property of the system.
2015,
27: 024145.
doi: 10.11884/HPLPB201527.024145
Abstract:
By taking advantages of the ultrasonic effects of dispersion, crushing, activation and initiation, the nano-aluminium/polystyrene (nano-Al/PS) encapsulation particles were prepared. The nano-Al particles were surface pretreated with the surfactants under ultrasonic irradiation. Then, the dispersion polymerization of styrene was initiated on the surface of nano-Al particles through ultrasonic irradiation in ethanol medium. In this reaction, the stabilizer was poly(N-vinyl pyrrolidone) (PVP), and the initiator was 2,2-azobisizobutyronitrile (AIBN). Finally, the encapsulation particles were respectively characterized by SEM, TEM, FTIR, thermogravimetric analysis (TGA), X-ray diffraction patterns (XRD) and X-ray photoelectron spectroscopy (XPS). The results showed that the size of nano-Al/PS encapsulation particles were about 2.0m. The polystyrene encapsulated nano-Al particles structure had good sphericity and smooth intact surface. Key words: nano-aluminium/polystyrene; encapsulation particles；dispersion polymerization；ultrasonic irradiation
By taking advantages of the ultrasonic effects of dispersion, crushing, activation and initiation, the nano-aluminium/polystyrene (nano-Al/PS) encapsulation particles were prepared. The nano-Al particles were surface pretreated with the surfactants under ultrasonic irradiation. Then, the dispersion polymerization of styrene was initiated on the surface of nano-Al particles through ultrasonic irradiation in ethanol medium. In this reaction, the stabilizer was poly(N-vinyl pyrrolidone) (PVP), and the initiator was 2,2-azobisizobutyronitrile (AIBN). Finally, the encapsulation particles were respectively characterized by SEM, TEM, FTIR, thermogravimetric analysis (TGA), X-ray diffraction patterns (XRD) and X-ray photoelectron spectroscopy (XPS). The results showed that the size of nano-Al/PS encapsulation particles were about 2.0m. The polystyrene encapsulated nano-Al particles structure had good sphericity and smooth intact surface. Key words: nano-aluminium/polystyrene; encapsulation particles；dispersion polymerization；ultrasonic irradiation
2015,
27: 024146.
doi: 10.11884/HPLPB201527.024146
Abstract:
The resonator fiber optic gyro will be the next-generation fiber-optic gyro following the interferometric fiber optic gyroscope due to its small size, high sensitivity, low power consumption, high reliability, and long life. As the core sensitive unit of resonator gyro, characteristics of transmission spectrum and the corresponding frequency discriminator curve in optical resonator become the key to improving the detection sensitivity of the optical gyro system. The experimental system is designed and built. The splitting ratio of the fiber coupler is 50:50. The fiber ring resonator is made by polarization maintaining fiber whose diameter and length are 17 cm and 2.2 m respectively. Piezoelectric transducer of narrow linewidth laser (linewidth is less than 1 kHz) is scanned by direct-current high voltage amplifier whose scanning frequency and voltage are 20 Hz and 1 V respectively. The analog circuit feedback system is adopted with proportional integral locking technique, so the output frequency of the laser can track the frequency of the resonator in real time. The transmission spectrum and discriminator curve of the fiber ring resonator are analyzed in two different cases. Firstly, the modulation voltages are 2 V and 4 V with a modulation frequency from 100 kHz to 4 MHz; Secondly, the modulation frequency is 900 kHz with a modulation voltage from 2 V to 10 V. Different varieties of seven parameters are obtained, such as the depth of resonance, the full width at half-maximum, the bandwidth, the dynamic range of linear zone, the quality factor, the scale factor and the precision of lock-in frequency. Moreover, three optimum modulation frequency and matched modulation voltage are obtained under static test conditions. These conclusions provide a guidance for further study on laser modulation effect on the spectrum of fiber ring resonators.
The resonator fiber optic gyro will be the next-generation fiber-optic gyro following the interferometric fiber optic gyroscope due to its small size, high sensitivity, low power consumption, high reliability, and long life. As the core sensitive unit of resonator gyro, characteristics of transmission spectrum and the corresponding frequency discriminator curve in optical resonator become the key to improving the detection sensitivity of the optical gyro system. The experimental system is designed and built. The splitting ratio of the fiber coupler is 50:50. The fiber ring resonator is made by polarization maintaining fiber whose diameter and length are 17 cm and 2.2 m respectively. Piezoelectric transducer of narrow linewidth laser (linewidth is less than 1 kHz) is scanned by direct-current high voltage amplifier whose scanning frequency and voltage are 20 Hz and 1 V respectively. The analog circuit feedback system is adopted with proportional integral locking technique, so the output frequency of the laser can track the frequency of the resonator in real time. The transmission spectrum and discriminator curve of the fiber ring resonator are analyzed in two different cases. Firstly, the modulation voltages are 2 V and 4 V with a modulation frequency from 100 kHz to 4 MHz; Secondly, the modulation frequency is 900 kHz with a modulation voltage from 2 V to 10 V. Different varieties of seven parameters are obtained, such as the depth of resonance, the full width at half-maximum, the bandwidth, the dynamic range of linear zone, the quality factor, the scale factor and the precision of lock-in frequency. Moreover, three optimum modulation frequency and matched modulation voltage are obtained under static test conditions. These conclusions provide a guidance for further study on laser modulation effect on the spectrum of fiber ring resonators.
2015,
27: 024147.
doi: 10.11884/HPLPB201527.024147
Abstract:
The fabrication and characterization of a micro-grating accelerometer with optoelectronic read out is described. The sensor consists of an Al membrane at the bottom of the bulk silicon proof mass and a rigid Au grating on the transparent substrate respectively. Optical detection is performed by measuring the reflected diffraction orders when the grating is illuminated through the quartz. The diffraction-based optical accelerometer is fabricated with silicon-glass anodic bonding procedure. This process is employed extensively in MEMS for its simplification and robustness. Experiment results show that the acceleration sensor has a displacement sensitivity of about 8 mV/nm and an acceleration sensitivity of about 5.6g-1 V. These results provide the reference for design and fabrication of the novel integrated micro-grating accelerometer.
The fabrication and characterization of a micro-grating accelerometer with optoelectronic read out is described. The sensor consists of an Al membrane at the bottom of the bulk silicon proof mass and a rigid Au grating on the transparent substrate respectively. Optical detection is performed by measuring the reflected diffraction orders when the grating is illuminated through the quartz. The diffraction-based optical accelerometer is fabricated with silicon-glass anodic bonding procedure. This process is employed extensively in MEMS for its simplification and robustness. Experiment results show that the acceleration sensor has a displacement sensitivity of about 8 mV/nm and an acceleration sensitivity of about 5.6g-1 V. These results provide the reference for design and fabrication of the novel integrated micro-grating accelerometer.
2015,
27: 024148.
doi: 10.11884/HPLPB201527.024148
Abstract:
Performance of resonator micro optic gyro (RMOG) is inevitably affected by modulation parameters. The influences on the RMOG by the frequency and amplitude of the modulation triangular wave have been deeply analyzed. Theoretical analysis and Matlab simulation results show that the modulation amplitude should be set to 15.44 V to obtain better carrier suppression ratio (CSR). The outputs of photodetectors are calculated by Matlab and the modulation frequency should be set to 1 MHz to improve signal to noise ratio (SNR). Then the experimental setup is established and the related measurements are performed. The test results are in good agreement with the analytical simulation. Moreover, the bias stability of the RMOG is improved from 0.39 ()/s to 0.18 ()/s (10 s integration time) over 600 s with the optimized modulation parameters. For other modulation techniques, such as sine wave phase modulation technique, the modulation parameters can also be optimized by analyzing the CSR and SNR to improve the bias stability of the RMOG.
Performance of resonator micro optic gyro (RMOG) is inevitably affected by modulation parameters. The influences on the RMOG by the frequency and amplitude of the modulation triangular wave have been deeply analyzed. Theoretical analysis and Matlab simulation results show that the modulation amplitude should be set to 15.44 V to obtain better carrier suppression ratio (CSR). The outputs of photodetectors are calculated by Matlab and the modulation frequency should be set to 1 MHz to improve signal to noise ratio (SNR). Then the experimental setup is established and the related measurements are performed. The test results are in good agreement with the analytical simulation. Moreover, the bias stability of the RMOG is improved from 0.39 ()/s to 0.18 ()/s (10 s integration time) over 600 s with the optimized modulation parameters. For other modulation techniques, such as sine wave phase modulation technique, the modulation parameters can also be optimized by analyzing the CSR and SNR to improve the bias stability of the RMOG.
2015,
27: 024149.
doi: 10.11884/HPLPB201527.024149
Abstract:
A new semicontinuum model is presented to analyze the dynamic characteristics of silicon nanobeam in this paper. Compared with tradition continuum theory, the new model utilizes the Keating potential and accounts for the discrete nature in the thickness and width directions of the nanobeam. Referring to Sun-Zhang model and using energy conservation theory, the modified Keating model is built. Then the fundamental frequencies of nanoscale clamped-clamped silicon beam are calculated, and the surface effect is considered into the calculation. It is shown that the results based on the new model coincide well either with the results using Material StudioTM software in nano-size or with those based on the continuum model in micro-size. Meanwhile, the model can reflect the fundamental frequency changing with the width, it also accords with the actual experiment.
A new semicontinuum model is presented to analyze the dynamic characteristics of silicon nanobeam in this paper. Compared with tradition continuum theory, the new model utilizes the Keating potential and accounts for the discrete nature in the thickness and width directions of the nanobeam. Referring to Sun-Zhang model and using energy conservation theory, the modified Keating model is built. Then the fundamental frequencies of nanoscale clamped-clamped silicon beam are calculated, and the surface effect is considered into the calculation. It is shown that the results based on the new model coincide well either with the results using Material StudioTM software in nano-size or with those based on the continuum model in micro-size. Meanwhile, the model can reflect the fundamental frequency changing with the width, it also accords with the actual experiment.
2015,
27: 024150.
doi: 10.11884/HPLPB201527.024150
Abstract:
In order to study the nanoscratch properties of optical quartz glass, a three-dimensional simulation of the fused silica is carried out based on molecular dynamics method. The model of the fused silica is established by using the approach of melting-quenching and the forming mechanism of the microscopic void in the process of preparation is analyzed by observing the sectional view. During the nanoscratch simulation, the change of the fused silica model and the movement of the atoms around the pore are observed and the cutting force curve is drawn. The influence of the void on the nanoscratch performance is obtained. The results show that the gaps in the fused silica are formed in the cooling process due to the restructuring of the covalent bond and their average diameter is about 0.25 nm. The voids will greatly reduce the existence of material mechanical properties, which causes the fluctuations of the cutting force. When the abrasive sweeps away, the atomic dense area, the thickness of 2 nm, is formed beneath the surface because the voids are compressed. The atomic populated area is the damaged layer due to the loss of strength of the original covalent bonds. Therefore the method of small quantities in high frequency can be applied to increasing the mechanical properties in the ultra-precision machining of quartz glass.
In order to study the nanoscratch properties of optical quartz glass, a three-dimensional simulation of the fused silica is carried out based on molecular dynamics method. The model of the fused silica is established by using the approach of melting-quenching and the forming mechanism of the microscopic void in the process of preparation is analyzed by observing the sectional view. During the nanoscratch simulation, the change of the fused silica model and the movement of the atoms around the pore are observed and the cutting force curve is drawn. The influence of the void on the nanoscratch performance is obtained. The results show that the gaps in the fused silica are formed in the cooling process due to the restructuring of the covalent bond and their average diameter is about 0.25 nm. The voids will greatly reduce the existence of material mechanical properties, which causes the fluctuations of the cutting force. When the abrasive sweeps away, the atomic dense area, the thickness of 2 nm, is formed beneath the surface because the voids are compressed. The atomic populated area is the damaged layer due to the loss of strength of the original covalent bonds. Therefore the method of small quantities in high frequency can be applied to increasing the mechanical properties in the ultra-precision machining of quartz glass.
2015,
27: 024151.
doi: 10.11884/HPLPB201527.024151
Abstract:
Fluid drag in the micro/nano fluidics is an object of scientific interest and surface charge at the solid-liquid interfaces is believed to affect fluid drag. How to measure the surface charge density and analyze the origin of surface charge at the solid-liquid interfaces are significant. Because the electrostatic force is related to the surface charge density and colloidal probe AFM can measure the electrostatic force with nanoscale resolution, a theoretical model between the electrostatic force applied on the AFM colloidal probe and the surface charge density at the solid-liquid interface is first developed and a method based on AFM is developed. Then the newly developed method is used to measure the surface charge densities of borosilicate glass and silica surfaces immersed in deionized (DI) water and 0.01 mol/L saline solution with pH value range from 3 to 10. The results show that borosilicate glass and silica surfaces in DI water and 0.01 mol/L saline solution are negatively charged because of the dissociation of silanol groups. Both the increasing pH value and ionic concentration can result in the increasing surface charge density of borosilicate glass and silica surface immersed in DI water and 0.01 mol/L saline solution. Furthermore, the colloidal probe AFM method is a useful technique to measure the surface charge density with high resolution.
Fluid drag in the micro/nano fluidics is an object of scientific interest and surface charge at the solid-liquid interfaces is believed to affect fluid drag. How to measure the surface charge density and analyze the origin of surface charge at the solid-liquid interfaces are significant. Because the electrostatic force is related to the surface charge density and colloidal probe AFM can measure the electrostatic force with nanoscale resolution, a theoretical model between the electrostatic force applied on the AFM colloidal probe and the surface charge density at the solid-liquid interface is first developed and a method based on AFM is developed. Then the newly developed method is used to measure the surface charge densities of borosilicate glass and silica surfaces immersed in deionized (DI) water and 0.01 mol/L saline solution with pH value range from 3 to 10. The results show that borosilicate glass and silica surfaces in DI water and 0.01 mol/L saline solution are negatively charged because of the dissociation of silanol groups. Both the increasing pH value and ionic concentration can result in the increasing surface charge density of borosilicate glass and silica surface immersed in DI water and 0.01 mol/L saline solution. Furthermore, the colloidal probe AFM method is a useful technique to measure the surface charge density with high resolution.
2015,
27: 024152.
doi: 10.11884/HPLPB201527.024152
Abstract:
Homojunction structure involved p/n-doped layers in the organic charge transport layers of organic light-emitting diodes (OLEDs) was developed to achieve chromaticity-tunable white OLEDs. This structure based on a single-layer structure which had a bipolar host material and co-dopant of complementary blue and yellow emitters, A relatively low turn-on voltage of 5.6 V, a high current efficiency of 2.64 cd/A and a low efficiency roll-off were achieved. Moreover, the Commission Internationale dEclairage coordinates varied from (0.41, 0.43) to (0.32, 0.35), which shifted almost along with the Planckian locus as the luminance increased. In addition, the charge carrier transport properties and recombination mechanisms were investigated and analyzed.
Homojunction structure involved p/n-doped layers in the organic charge transport layers of organic light-emitting diodes (OLEDs) was developed to achieve chromaticity-tunable white OLEDs. This structure based on a single-layer structure which had a bipolar host material and co-dopant of complementary blue and yellow emitters, A relatively low turn-on voltage of 5.6 V, a high current efficiency of 2.64 cd/A and a low efficiency roll-off were achieved. Moreover, the Commission Internationale dEclairage coordinates varied from (0.41, 0.43) to (0.32, 0.35), which shifted almost along with the Planckian locus as the luminance increased. In addition, the charge carrier transport properties and recombination mechanisms were investigated and analyzed.
2015,
27: 024153.
doi: 10.11884/HPLPB201527.024153
Abstract:
Gold flower-like nanoarrays based on nanosphere lithography (NSL) have been fabricated for Raman enhancement. After spin-costing of 509 nm polystyrene nanosphere and O2 etching of the substrate, deposition and annealing make the gold nanoarrays bulging, forming the flower-like nanoarrays. FDTD simulation of the nanostructures shows that these nanoarrays show high electromagnetic enhancement. Main enhancements are on the edges of the substrate. At last, Raman tests using Rhodamine 6G indicate that these nanoarrays show high Raman intensity when comparing with that of Au substrate. Minimum Rhodamine 6G detection limit of these arrays can reach the level of 10-6 mol/L.
Gold flower-like nanoarrays based on nanosphere lithography (NSL) have been fabricated for Raman enhancement. After spin-costing of 509 nm polystyrene nanosphere and O2 etching of the substrate, deposition and annealing make the gold nanoarrays bulging, forming the flower-like nanoarrays. FDTD simulation of the nanostructures shows that these nanoarrays show high electromagnetic enhancement. Main enhancements are on the edges of the substrate. At last, Raman tests using Rhodamine 6G indicate that these nanoarrays show high Raman intensity when comparing with that of Au substrate. Minimum Rhodamine 6G detection limit of these arrays can reach the level of 10-6 mol/L.
2015,
27: 024154.
doi: 10.11884/HPLPB201527.024154
Abstract:
A miniaturized electrochemical measurement system for nitrate detection is presented. In the system, a renewable copper-clusters modified working electrode and a Pt counter electrode fabricated on a glass substrate by micro-electro-mechanical system technique were used to detect the concentration of nitrate in water. A low-noise, high-precision potentiostat module was designed to realize the electrode position of fresh copper onto the working electrode, the generation of linear sweep voltage and the detection of the response current with the magnitude of A-mA. STM32F407 microcontroller was applied to control the measuring process and display the detection results on a capacitive touch screen. The experimental results show that the developed system has a good linearity of 0.996 with the concentration of nitrate ranging from 0 to 71.4 molL-1. In comparison with the detection results by electrochemical workstation, the developed system has similar performances.
A miniaturized electrochemical measurement system for nitrate detection is presented. In the system, a renewable copper-clusters modified working electrode and a Pt counter electrode fabricated on a glass substrate by micro-electro-mechanical system technique were used to detect the concentration of nitrate in water. A low-noise, high-precision potentiostat module was designed to realize the electrode position of fresh copper onto the working electrode, the generation of linear sweep voltage and the detection of the response current with the magnitude of A-mA. STM32F407 microcontroller was applied to control the measuring process and display the detection results on a capacitive touch screen. The experimental results show that the developed system has a good linearity of 0.996 with the concentration of nitrate ranging from 0 to 71.4 molL-1. In comparison with the detection results by electrochemical workstation, the developed system has similar performances.
2015,
27: 024155.
doi: 10.11884/HPLPB201527.024155
Abstract:
Spheric SiO2 nanoparticles with the sizes range in 10-100 nm are dispersed in nonaqueous solvent under the assistant of surfactant. Hydrogen bond bridge effect and long chain molecule spatial hindrance are two key roles for dispersion. The particles median size is 30.2 nm according to dynamic light scattering (DLS) test and exhibits nice agreement with transmission electron microscopy(TEM) result under optimal surfactant volume ratio of 6%.
Spheric SiO2 nanoparticles with the sizes range in 10-100 nm are dispersed in nonaqueous solvent under the assistant of surfactant. Hydrogen bond bridge effect and long chain molecule spatial hindrance are two key roles for dispersion. The particles median size is 30.2 nm according to dynamic light scattering (DLS) test and exhibits nice agreement with transmission electron microscopy(TEM) result under optimal surfactant volume ratio of 6%.
2015,
27: 024156.
doi: 10.11884/HPLPB201527.024156
Abstract:
The Au-doped melamine-formaldehyde(MF) aerogel was fabricated by-irradiation of AuCl3solution with MF aerogel monoliths impregnated. The obtained samples were characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDX) and transmission electron microscope (TEM). The results show that the well distributed Au nanoparticles presented in MF aerogels and the average particle size was 5.8 nm after irradiation. The nitrogen adsorption characterization reveals the introduction of Au nanoparticles produced a reduction of the surface areas and total, micropore and mesopore volumes.
The Au-doped melamine-formaldehyde(MF) aerogel was fabricated by-irradiation of AuCl3solution with MF aerogel monoliths impregnated. The obtained samples were characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDX) and transmission electron microscope (TEM). The results show that the well distributed Au nanoparticles presented in MF aerogels and the average particle size was 5.8 nm after irradiation. The nitrogen adsorption characterization reveals the introduction of Au nanoparticles produced a reduction of the surface areas and total, micropore and mesopore volumes.
2015,
27: 024157.
doi: 10.11884/HPLPB201527.024157
Abstract:
The structural internal forces as well as properties may be changed by galvanic corrosion. Studying and understanding the laws of galvanic corrosion effects on structural internal forces is useful for promotion of design level. The experiments and measurements of macro compressed loading and corrosion for a pair of galvanic electrodes subjected to fixed displacement loading are performed and the curve of the compressive force between the galvanic electrodes versus corrosion time is obtained. According to the corroded surface morphologies obtained by scanning electron microscope (SEM) after rust cleaning, the meso-scale finite element model for the corroded zone is developed by using the homogenization method in terms of representative volume element (RVE) and the equivalent elasticity constants of the corroded zone are computed. Meanwhile, the sizes of the corroded zone are determined approximately by the corroded surface morphologies and a macro-scale finite element model for the whole sample is developed and the compressive force is calculated which basically agrees well with the experimental value. Therefore, a new method to numerically simulate the influences of galvanic corrosion on structural mechanical behavior is developed.
The structural internal forces as well as properties may be changed by galvanic corrosion. Studying and understanding the laws of galvanic corrosion effects on structural internal forces is useful for promotion of design level. The experiments and measurements of macro compressed loading and corrosion for a pair of galvanic electrodes subjected to fixed displacement loading are performed and the curve of the compressive force between the galvanic electrodes versus corrosion time is obtained. According to the corroded surface morphologies obtained by scanning electron microscope (SEM) after rust cleaning, the meso-scale finite element model for the corroded zone is developed by using the homogenization method in terms of representative volume element (RVE) and the equivalent elasticity constants of the corroded zone are computed. Meanwhile, the sizes of the corroded zone are determined approximately by the corroded surface morphologies and a macro-scale finite element model for the whole sample is developed and the compressive force is calculated which basically agrees well with the experimental value. Therefore, a new method to numerically simulate the influences of galvanic corrosion on structural mechanical behavior is developed.
2015,
27: 024158.
doi: 10.11884/HPLPB201527.024158
Abstract:
Six kinds of analytically pure compounds, SiO2, MnO2, CaO, TiO2, CaF2, and NaF, were used to make multi-component active fluxes. 500 m thick of GH4169 superalloy sheets were welded by active laser welding process using micro pulse laser equipment. Effects of fluxes on microstructure and mechanical properties of the joints were investigated and discussed. The results showed that the weld bead penetration was increased by all 20 series of active fluxes compared with conventional laser welding. The effect of series F12 was especially notable and the increment of depth to width ratio of the weld was 159%. It is feasible to increase weld penetration thus to improve welding efficiency and reduce welding consumption using active fluxes. Microstructures in active laser welding seams were columnar and equiaxed grains and the joint tensile strength is 927 MPa, which was 92.7% of the base metal strength.
Six kinds of analytically pure compounds, SiO2, MnO2, CaO, TiO2, CaF2, and NaF, were used to make multi-component active fluxes. 500 m thick of GH4169 superalloy sheets were welded by active laser welding process using micro pulse laser equipment. Effects of fluxes on microstructure and mechanical properties of the joints were investigated and discussed. The results showed that the weld bead penetration was increased by all 20 series of active fluxes compared with conventional laser welding. The effect of series F12 was especially notable and the increment of depth to width ratio of the weld was 159%. It is feasible to increase weld penetration thus to improve welding efficiency and reduce welding consumption using active fluxes. Microstructures in active laser welding seams were columnar and equiaxed grains and the joint tensile strength is 927 MPa, which was 92.7% of the base metal strength.
