Gao Yinlu, Sun Dan, Jiang Xue, Zhao Jijun
Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), Dalian University of Technology, Dalian 116024, People's Republic of China.
Science and Technology on Reactor System Design Technology Laboratory, Nuclear Power Institute of China, Chengdu, 610213, People's Republic of China.
J Phys Condens Matter. 2020 Oct 19;33(3). doi: 10.1088/1361-648X/abbdbb.
One of the major challenges for the GaN-based high-electron-mobility transistors (HEMTs) used as high power devices is to understand the effect of defects, especially on the band alignment. Usingcalculation, herein we investigate the variations of band offsets with interfacial structure, defect position, interface states and Al content in AlGaN/GaN heterostructures (= 0.06, 0.13, 0.19, 0.25). It was found that N vacancy (V) and Ga anti-site (Ga) introduce nonlocal interface states and the change of valence band offset (VBO) depends on the defect location. While the interface states induced by Ga vacancy (V) and N anti-site (N) show strong localization behavior, and their impact on VBO is independent on the defect position. The low symmetry of wurtzite nitride and the lattice mismatch between AlGaN and GaN will generate polarization charge (spontaneous polarization and piezoelectric polarization) at the interface. Along the direction of polarization field, Vand Galying in the AlGaN side change the VBO most pronouncedly. These theoretical results provide useful guidance for control of point defects in AlGaN/GaN HEMTs, which have profound impact on the performance and reliability of GaN-based devices.
用作高功率器件的氮化镓基高电子迁移率晶体管（HEMT）面临的主要挑战之一是了解缺陷的影响，尤其是对能带排列的影响。本文通过计算研究了AlGaN/GaN异质结构（= 0.06、0.13、0.19、0.25）中能带偏移随界面结构、缺陷位置、界面态和铝含量的变化。研究发现，氮空位（V）和镓反位（Ga）会引入非局域界面态，价带偏移（VBO）的变化取决于缺陷位置。而镓空位（V）和氮反位（N）诱导的界面态表现出强烈的局域化行为，它们对VBO的影响与缺陷位置无关。纤锌矿型氮化物的低对称性以及AlGaN和GaN之间的晶格失配会在界面处产生极化电荷（自发极化和压电极化）。沿极化场方向，位于AlGaN一侧的V和Ga对VBO的影响最为显著。这些理论结果为控制AlGaN/GaN HEMT中的点缺陷提供了有用的指导，这些缺陷对氮化镓基器件的性能和可靠性有深远影响。
