应力条件下AlGaN／GaN HEMT电流崩塌效应研究

A Study on Current Collapse in AlGaN/GaN HEMTs Induced by Bias Stress

采用应力测试方法,获得了AlGaN／GaN HEMT漏极电流随时间的变化关系。实验结果表明, 应力导致漏极电流崩塌56．2％;不同电压应力条件下,只要所加时间足够长和电压足够大,相同栅压的电流崩塌程度都近似相等;漏极电流恢复时间与大小分别为34．5+αVGS与α(VGS-VT)(2-βt)。研究表明,栅- 漏间表面态捕获的电子使得表面电势发生变化,引起沟道中二维电子气浓度降低,从而导致电流崩塌效应的产生。此结论可望用于AlGaN／GaN HEMT器件电流崩塌效应进一步的理沦探索和器件研究。

Bias stress measurement is adopted to acquire the AlGaN/GaN HEMTs＇ drain current variation which follows the time. The results show that the current is collapsed 56.2% induced by bias stress, and if the bias stress is long and large enough, current collapses are approximately even in the same gate voltage and different bias conditions. The analysis results revealed that the drain current recovery time and magnitude are 34.5＋σVGS and σ（VGS-VT）（2-β）, respectively. The investigation indicates that the surface electrons induced surface potential changes cause 2DEG density decreasing in channel, it is the main reason inducing current collapse. This conclusion can be assisted in further theory research and investigation for AlGaN/GaN HEMT devices.