矩形激光脉冲辐照下半导体温度场理论研究

摘要

In order to study three-dimensional photo-generated carrier density and temperature field distribution in semiconductor materials excited by the rectangular laser pulse , the analytical expressions of the temporal and space distributions of plasma wave and thermal wave were obtained by using the eigen function method .The time evolutions of the plasma and thermal wave for different characterized parameters of semiconductor samples and the radial diffusion characterizations of thermal wave in semiconductors were numerically simulated .The simulation results show that the characterized parameters of semiconductor samples such as surface recombination rates , lifetimes and diffusivity have important influences on temporal characteristics of plasma wave and thermal wave , especially at the stage of step changes . In addition , the sensitivity and correlation analysis of multi-parameters estimation shows that the characterization of single or two semiconductor parameters can be realized by fitting step response curve .The theoretical study provides the guidance for parameters measurement of semiconductor materials by the pulsed photothermal techniques using step optical excitation .%为了研究矩形激光脉冲辐照下半导体材料3维光生载流子浓度和温度场分布，采用本征函数法求得了等离子体波和热波随时间和空间变化的解析解。数值模拟了矩形激光脉冲辐照下半导体内光生载流子浓度和温度的时间变化规律以及温度沿径向的扩散规律。结果表明，光生载流子表面复合速率、寿命和扩散系数等参量对等离子体波和热波分布的时域特性有重要的影响，特别是在等离子体波和热波阶跃响应的上升和下降沿阶段；此外，多参量拟合灵敏度以及相关性分析表明，对阶跃响应曲线进行拟合可实现对半导体参量的单参量及双参量表征。该理论结果对于利用阶跃光激励的光热技术测量半导体材料参量具有一定的指导作用。