AlGaN/GaNHFET逆压电效应抑制技术

Reduction Technique of Inverse Piezoelectric Polarization Effect on AlGaN /GaN HFETs

基于非对称晶体的逆压电效应(IPPE),通过自洽求解一维Poisson-Schrdinger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。

Base on the inverse piezoelectronic polarization effect （IPPE） of asymmetric crystal, the change of 2DEG concentration in AlGaN/GaN HFET under the action of electric field was simulated, and the numerical IPPE model of current collapse effect was setted up through the self-consistent solution of one-dimensional Possion-Chrodinger equation. It is found that IPPE is one of the sources of current collapse. Base on the GaN ohmic contact mechanism, the source leakage groove structure was presented to reduce the vertical component of electric field, inhibit the IPPE, and reduce the change of the saturation current. The validation process flow sheet was proved, and the optimized device structure was obtained. The current collapse parameter of the device decreases from 15. 7% to 8.9%, so simulation results verify the theory.