调制自由载流子吸收测量半导体载流子输运参数的三维理论

推导出用于测量半导体载流子输运特性(载流子寿命、载流子扩散系数和前表面复合速度)的调制自由载流子吸收(modulated free carrier absorption, MFCA)检测技术的三维理论模型，给出了调制自由载流子吸收检测信号与调制频率和抽运-探测光相对距离的关系.定性分析了在不同调制频率时各个载流子输运参数对径向位置扫描曲线(信号与两束光相对距离的关系)的影响，结果表明调制自由载流子吸收检测信号对各个参数的灵敏度随抽运-探测光相对距离的增加而增加.仿真和实验结果表明，通过拟合不同调制频率时调 关键词： 调制自由载流子吸收 载流子输运特性 径向位置扫描

Measurement of electronic transport property of semiconductors by three-dimensional modulated free carrier absorption technique

A three-dimensional model for the modulated free carrier absorption (MFCA) is developed to measure the electronic transport properties (the carrier lifetime, the carrier diffusivity, and the front surface recombination velocity) of semiconductor wafers. The dependence of MFCA amplitude and phase on the electronic transport properties at different pump-probe-beam separation and different modulation frequencies is investigated. It is found that the sensitivities of MFCA signal to individual transport parameters increase with increasing two-beam separation. An experiment with a silicon wafer is performed and the carrier lifetime, carrier diffusivity, and front surface recombination velocity are determined simultaneously and unambiguously by fitting the observed values of the MFCA amplitude and phase as functions of the separation between the pump and probe laser spots, measured at several modulation frequencies covering an appropriate range.