用逆压电极化模型对AlGaN/GaN 高电子迁移率晶体管电流崩塌现象的研究

通过自洽求解一维Poisson-Schrdinger方程，模拟了AlGaN/GaN高电子迁移率晶体管在工作时等效外电场对AlGaN/GaN异质结沟道处二维电子气(2DEG)浓度的影响.分析了逆压电极化效应的作用，从正-逆压电极化现象出发，提出了逆压电极化模型.计算结果显示：逆压电极化明显影响2DEG性质，当Al组分x=0.3,AlGaN层厚度为20 nm时，不考虑逆压电极化，2DEG浓度为1.53×10¹³cm^-2；当等效外电压分别为10和15V 关键词： AlGaN/GaN高电子迁移率晶体管 Poisson-Schrdinger方程 逆压电极化模型 电流崩塌

Research on the current collapse in AlGaN/GaN high-electron-mobility transistors through the inverse piezoelectric polarization model

Current collapse in AlGaN/GaN high-electron-mobility transistors was studied and the effect of effective external electrical field on the concentration of two-dimensional electron gas (2DEG) near the channel of hetero-junction of AlGaN/GaN was simulated through the self-consistent implementation of the one-dimensional Poisson-Schrdinger equations. An inverse piezoelectric polarization model was proposed to analyze the degradation of 2DEG and the current collapse. It was found that the density of 2DEG was strongly dependent on the inverse polarization. When the voltage was 0,10 and 15 V, the density was 1.53×10¹³cm^-2, 1.04×10¹³cm^-2 and 0.789×10¹³cm^-2, respectively. It was clear that the 2DEG density dropped 48.4% with voltage increasing from 0 to 15V when the inverse piezoelectric polarization was considered. At last, the method of restraining current collapse was further discussed.