Numerical Explanation of Slow Transients in an AlGaN/GaN HEMT

观察了AlGaN/GaN HEMT器件在短期应力后不同栅偏置下的一组漏极电流瞬态,发现瞬态的时间常数随栅偏压变化很小,据此判断这组瞬态由电子陷阱的释放引起.为了验证这个判断,采用数值仿真手段计算了上述瞬态.分别考虑了在器件中不同空间位置的电子陷阱,分析了应力和瞬态中相应的陷阱行为,对比和解释了仿真曲线与测量结果的异同.基于上述讨论,提出测量的瞬态可能是表面深陷阱和GaN层体陷阱的综合作用的结果.

Numerical Explanation of Slow Transients in an AlGaN/GaN HEMT

A series of slow drain current recovery transients at different gate biases after a short-term stress are observed in an AlGaN/GaN HEMT.As the variation of the time constants of the transients is small,the working trap is determined to be electronic.A numerical simulation verifies this conclusion and reproduces the measured transients.The electron traps at different spatial positions in the device-on the ungated surface of the AlGaN layer,in the AlGaN barrier,and in the GaN layer are considered;corresponding behaviors in the stress and the transients are discussed;and for the simulated transients,agreement with and deviation from the measured transients are explained.Based on this discussion,we suggest that the measured transients are caused by the combined effects of a deep surface trap and a bulk trap in the GaN layer.