AlGaN/GaN HEMT栅阶跃脉冲响应实验研究

Investigation on the Response Dependence of Gate Step Pulse in AlGaN/GaN HEMT

通过对AlGaN/GaN HEMT漏极电流栅阶跃脉冲响应实验测试,发现栅脉冲相同时,HEMT开启时间在线性区随VDS增加而增加,而在饱和区随VDS增加而减小;在VDS一定时,器件开启时间随栅脉冲低电平的降低而增加。基于表面态电子释放过程与ID、VDS和阶跃脉冲之间关系的分析,提出了用快电子与慢电子释放两种过程来解释表面态电子弛豫,并建立漏极电流响应过程拟合算式。拟合得到与快、慢电子释放相关的时间常数分别为τ1=0.23s、τ2=1.38s,且拟合曲线与实验结果的最大误差不超过测试值的3%。该研究结果有助于电流崩塌机理的进一步探索。

The response dependence of drain current on gate step pulse in AlGaN/GaN HEMT was investigated. This result shows that the turning-on time of device increases in linear region and decreases in saturated region with the VDS rising under same gate pulse respectively, while it goes up with the decreasing of the pulse low-level at constant VDS. Analyzing the relation between electron detrapping and ID, VDS and gate pulse, we suggested that the relaxation of surface state electron included two processes, fast electron and slow electron detrapping, and obtained the fitting formula characterizing drain current response. By fitting, the time constants associated with fast and slow electron detrapping process were about 0.23 s and 1.38 s respectively. The error between the fitting and experimental result is less than 3%.