瞬态光响应法测试中波碲镉汞器件少子寿命的新方法

A New Method for Measuring The Minority Carrier Lifetime of MWIR HgCdTe Materials by Transient Photoresponse Method

在测试中波碲镉汞光伏器件的瞬态响应时,当激光光斑照射器件表面位置距离光敏面较远时,器件表现为特殊的双峰脉冲响应现象,分析表明出现这种异常双脉冲现象的原因是光敏区内的少子漂移和光敏区外侧向收集的少子扩散有时间上的差异。通过对器件施加反向偏压,脉冲响应随反向偏压的增大由双峰变成单峰的实验结果,验证了少子侧向收集是导致器件形成双峰的主要原因。对第二个峰拟合得到p区的少数载流子寿命。将瞬态响应获得的少子寿命与该p型中波碲镉汞材料的理论计算和光电导衰退法得到的少子寿命相对比,发现三种方式得到的少子寿命随温度的变化趋势基本一致,这说明了可以通过瞬态光响应得到中波碲镉汞器件的少子寿命。

When measuring the transient response of MWIR HgCdTe photovoltaic devices,the device presented a special bimodal pulse response phenomenon when the surface position of the device irradiated by the laser spot was far away from the photosensitive surface.It is analyzed that the abnormal double pulse phenomenon was due to the time difference between the drift of minority carriers in the photosensitive region and the diffusion of minority carriers collected laterally outside the photosensitive region.By applying reverse bias to the device,the impulse response changed from bimodal to unimodal with the increase of reverse bias,which verified that the lateral collection of minority carriers was the main reason for the bimodal formation of the device.The minority carrier lifetime of p-region materials was obtained by fitting the second peak.Comparing the minority carrier lifetime obtained from the transient response with that obtained by the theoretical calculation and the photoconductivity decay method of the p-type MWIR HgCdTe material,it is found that the trends of the minority carrier lifetime obtained from the three methods with temperature are basically the same,which indicates that the minority carrier lifetime of MWIR HgCdTe material can be obtained from the transient photoresponse.