Effect of laser excitation energy on resistance of lateral geometry 4H-SiC photoconductive semiconductor switches

The lateral geometry 4H-SiC photoconductive semiconductor switches (PCSS) were fabricated on the vanadium compensated semi-insulating 4H-SiC substrate with the Si (0001) Ni/Au contacts deposited by magnetron sputtering. The effect of laser excitation energy on the photoelectric response and that on the state resistance of PCSS were investigated. The experimental results showed that a nano-second pulse electric signal was obtained when the PCSS was triggered with a 532 nm wavelength laser light. The on state resistance decreased from 295 to 197 when the laser excitation energy increased from 26.7 mJ to 43.9 mJ. Based on the combination theory, the relationship between the carrier concentration and time deduced when the PCSS was irradiated. The on state resistance simulated from the MATLAB is consistent with the experimental results. Finally, the two ways to reduce the on resistance of the switch are put forward.