【作者】 刘冰；

【导师】 吕燕伍；

【作者基本信息】 北京交通大学 ， 光学， 2013， 博士

【摘要】 三族氮化物半导体材料因其诸多优点,成为了近年来研究的热点,其中GaN基高电子迁移率晶体管(HEMT)具有广泛的应用前景。本论文的主要研究内容是GaN-HEMT中的基本结构--氮化镓异质结--中二维电子气的子带能级、面密度、分布、以及其被散射所限制的迁移率的情况。首先使用自洽求解泊松方程和薛定谔方程的方法分析计算了AlGaN/GaN异质结中二维电子气的子带能带和电子分布情况,计算中使用了全新的利用肖特基势垒高度确定费米能级的方法。然后介绍了较为重要的散射机制如界面粗糙散射、合金无序散射、极性光学声子散射的处理方法,并利用电子平均热动能对温度的依赖关系,得到了温度对缺陷散射强度的影响。最后提出了两种全新的散射机制,表面粗糙散射和界面失配位错散射,对其做了详尽的说明和计算,结果表明它们对电子的散射都有显著的作用。所使用的处理方法可以适用于氮化镓异质结以外的其他的异质结体系。本论文的工作对器件设计和相应的实验工作有很好的指导意义。更多还原

【Abstract】 Group III nitride semiconductor materials have received much attention, and become a research hot spot in recent years. GaN-based high electron mobility transistors (HEMT) have broad potential application prospects. The main contents of this thesis is to investigate the sub-band energy levels, the density, the distribution, and the mobility of two dimensional electron gas (2DEG) in group III nitride heterojunctions, which is from basic structure of GaN-HEMTs.First of all, by solving the Poisson equation and Schrodinger equation self-consistently, we obtain the sub-band energy levels and electron distribution of2DEG. Schottky barrier height was using to determine the Fermi energy level, which is a new method for that.In the following chapter, several important scattering mechanisms, such as interface roughness scattering, alloy disorder scattering, polar optical phonon scattering are introduced. The dependence of defect scattering rate to temperature was studied by taking the dependence of the electron thermal kinetic energy on temperature into account.Finally, two new scattering mechanisms, surface roughness scattering and interfacial misfit dislocation scattering, are presented with detailed description and calculation. Results show that they play significant roles to scatter the electron. The used method of treatment can be applied not only to GaN heterojunction but also to other type heterojunction systems.Work of this thesis is a good guidance for application.更多还原