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AlGaN/4H-SiC异质结界面存在大的自发和压电极化效应,从而使界面出现较多数量的极化电荷,这导致器件电学性能的改变。利用热场发射-扩散模型,基于数值模拟方法研究了异质结界面极化效应产生的极化电荷对AlGaN/4H-SiC HBT器件直流性能和高频性能的影响。得到了AlGaN/4H-SiC异质结界面极化效应引诱的正极性极化界面电荷削弱了异质结的内建电场,加速了载流子的扩散运动,因而能促进载流子的输运,从而使器件的直流特性和高频特性得到改善。
AlGaN / 4H-SiC heterojunction interface has a large spontaneous and piezoelectric polarization effect, so that the interface appears a large number of polarized charges, which led to changes in the electrical properties of the device. The effects of polarization charges generated by heterojunction interface polarization on the DC performance and high frequency performance of AlGaN / 4H-SiC HBT devices were investigated by using the thermal field emission-diffusion model. The positive polarization interface induced by the polarization effect of the AlGaN / 4H-SiC heterojunction interface is obtained, which weakens the built-in electric field of the heterojunction and accelerates the diffusion of carriers, thus facilitating the transport of carriers , So that the DC characteristics and high frequency characteristics of the device is improved.