脉冲激光烧蚀Ge产生等离子体特性的数值模拟
Numerical simulation on plasma characteristics of Ge ablated by pulse laser
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摘要: 针对激光烧蚀半导体材料Ge初期的特点，建立了1维的热传导和流体动力学模型。对波长为248 nm、脉宽为17 ns、峰值功率密度为4×108 W/cm2的KrF脉冲激光在133.32 Pa氦气环境下烧蚀Ge产生等离子体的特性进行了数值模拟。结果表明：单个激光脉冲对靶的烧蚀深度达到55 nm，蒸气膨胀前端由于压缩背景气体产生压缩冲击波, 波前的速度最大，温度很高。从不同时刻的电离率分布图中得出，在靶面附近区域，Ge的1阶电离始终占优势；在中心区域，脉冲作用时间内，Ge的2阶电离率比1阶电离率大，脉冲结束后，Ge的2阶电离率下降，1阶电离率逐渐变大。Abstract: In the early stage of UV excimer laser ablation of semiconductor, plasma induced by laser ablation was assumed at local thermodynamic equilibrium. One-dimension hydrodynamic model is presented for the laser ablation of Ge in a background gas (He) at 133.32 Pa and the characteristics of plasma induced by Gaussian-shaped KrF laser pulse with wavelength of 248 nm, pulse width of 17 ns, and peak power of 4×108 W/cm2. The results show that the ablated depth arrives 55 nm after laser pulse irradiation. The background gas He is gradually pushed away by the Ge vapor, forming a compression shock wave. And the maximum temperature always locates at the front of the shock wave. Spatial distribution of ionization degrees at different time shows that the first-order ionization degree of Ge always domin
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Key words:
- pulsed laser ablation deposition /
- pulsed laser ablation /
- plasma /
- ge crystal
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