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基于非对称晶体的逆压电效应(IPPE),通过自洽求解一维Poisson-Schrdinger方程,模拟了AlGaN/GaN HFET在外电场作用下沟道中2DEG浓度的变化,建立了电流崩塌效应的逆压电效应数值仿真模型。理论模拟显示:逆压电效应是引起电流崩塌效应的一个因素。根据GaN欧姆接触的机理,提出采用源漏凹槽的结构减小电场的垂直分量,抑制逆压电效应,减小饱和电流的变化。设计了不同结构的源漏凹槽结构器件,并进行工艺流片验证,得到优化的器件结构,器件的电流崩塌量从15.7%减小到8.9%,验证了理论仿真结果。
Based on the inverse piezoelectric effect (IPPE) of asymmetric crystals, the one-dimensional Poisson-Schrödinger equation was solved by self-consistent method to simulate the change of 2DEG concentration in the channel of AlGaN / GaN HFET under external electric field. The inverse of current collapse effect Piezoelectric Effect Numerical Simulation Model. The theoretical simulation shows that the inverse piezoelectric effect is a factor that causes the current collapse effect. According to the mechanism of GaN ohmic contact, the structure of the source / drain recess is proposed to reduce the vertical component of the electric field, suppress the reverse piezoelectric effect and reduce the variation of the saturation current. The source and drain trench structures with different structures were designed and verified by the process flow. The optimized device structure was obtained. The current collapse amount of the device was reduced from 15.7% to 8.9%, which verified the theoretical simulation results.