双面抛光单晶硅片少子扩散长度的测量

Determination of Minority Carrier Diffusion Length in Both Sides Polished Silicon Wafers by SPV Method

本文改进了常规表面光电压测试少子扩散长度法,采用环形下电极消除了薄样品背面光电压信号对测量结果的影响;应用阻尼最小二乘法数据处理原理对实验数据进行“曲线拟合”,求出少子扩散长度和背面表面复合速度。本文讨论了该方法的测量范围。

The authors improved the routine steady-state surface photovoltage method to measure minority carrier diffusion length in both sides polished silicon wafers. We use a copper ring as a back contact with the silicon wafer,then the back surface photovoltage signal is not detected,only the front surface photo-voltage signal is measured. Considering the effect of the back surface recombination we solved the minority carrier continuity equation and obtained the theoretical relationship between the incident photon flux and the absorption coefficient,in which there are some parameters (minority carrier diffusion length,back surface recombination velocity etc. ). By means of the damped least squares method to fit the experimental data with the theoretical curve we obtained the minority carrier diffusion length and the back surface recombination velocity. This paper also discussed the applied conditions of the method.