用红外光激励电流法研究非晶半导体带隙态分布

本文提出了用红外光激励电流法研究非晶半导体带隙态的新方法。当一本征脉冲光照射样品时,大量非平衡载流子陷落到带隙态上;经过延迟时间t_d,用红外光激励残存的非平衡载流子,能引起红外光电导的过冲,过冲量与延迟时间t_d成幂次关系。基于多次陷落模型分析红外光电导过冲与温度及时间t_d的关系,可以得到带隙态分布的细节。关键词：

MEASUREMENT OF THE DENSITY OF GAP STATES IN AMORPHOUS SEMICONDUCTORS BY INFRARED STIMULATED CURRENTS

A new method of measuring the density of gap states in amorphous semiconductors by employing a two-beam photoconductivity experiment is reported. In the two-beam experiment, an intensive bandgap pump light is used to create non-equilibrium carriers and most of these carriers are trapped in the gap states. Then, at a latter time t_d after turning off the pump light, these trapped carriers are re-excited by an infrared probe light A photoconductivity overshoot, which depends on the delay time and temperature, is observed in the onset process of IR excited photoconductivity. The results are discussed using the multiple trapping theory. The distribution of the density of gap states is deduced from the experiment.