表面光电压测量中的最佳相位

The Optimal Phase in the Measurement of SPS

对基于锁相放大技术的表面光电压测量中的“最佳相位”的物理意义及影响因素进行了系统的理论分析及实验验证．结果表明，对于通常所采用的金属-绝缘体-半导体(MIS)“三明治”测量结构，其等效阻抗会很大程度地影响到最佳相位．对于体相材料，“最佳相位”仅与测量条件有关；对于纳米材料等体系，光照可以改变MIS 结构的等效电阻(R_(ins))、等效电容(C_(ins))，从而将引起最佳相位角的显著变化，使“最佳相位”与所研究材料的特性直接关联起来，因此，该手段有可能成为一种新的纳米材料光电检测方法。

The physical meanings and affecting factors of the optimal phase are analyzed and validated systematically in the measurement of surface photovoltage spectroscopy (SPS) based on Lock-In amplifier. Taking the example of p silicon, under different modulation frequences the measured data of the optimal phase were in agreement with the theoretical analysis, which shows that for the usual metal-insulator-semiconductor (MIS) 'sandwich' structure, the equivalent impedance can greatly affect the optimal phase. In the case of bulk materials, the optimal phase only correlates with experimental conductions. But for nanomaterials, the equivalent resistance and capacitance ( R-ins andC(ins)) of MIS structure vary under illumination that will result in great changes in the optimal phase. Because R-ins and C-ins are related to the characters of nanomaterials, the optimal phase may offer a new method for the measurement of photo-electric properties of nanomaterials.