Kaewmeechai Chaiyawat, Laosiritaworn Yongyut, Jaroenjittichai Atchara Punya
Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, 239 Huay Kaew Road, Chiang Mai 50200, Thailand.
Research Center in Physics and Astronomy, Faculty of Science, Chiang Mai University, 239 Huay Kaew Road, Chiang Mai 50200, Thailand.
J Phys Condens Matter. 2020 Oct 20;33(3). doi: 10.1088/1361-648X/abbe7f.
We investigated band alignment of non-polar and polar GaN/AlN heterojunction by using density functional theory with the Heyd-Scuseria-Ernzerhof hybrid functional. In the heterojunction model, AlN was considered as a substrate while strained GaN was grown on top. The deformation potential of GaN, were included to calculate the unstrained band offsets. For polar heterojunction, the artificial effects from an undesired interface was removed by using vacuum insertion and dipole correction. We found that the unstrained valence band offsets (VBOs) are 0.92 eV, 1.23 eV and 1.09 eV for non-polar, Ga-polar and Al-polar interfaces respectively. The variation of VBOs can be explained from the difference in both deformation and dipole potential at the interfaces. Moreover, the additional energy shift of polar VBO from non-polar VBO were extracted as 0.33 eV from considering the effect of spontaneous polarization.
我们使用含Heyd-Scuseria-Ernzerhof杂化泛函的密度泛函理论研究了非极性和极性GaN/AlN异质结的能带排列。在异质结模型中,AlN被视为衬底,而应变GaN生长在其上。计算未应变能带偏移时包含了GaN的形变势。对于极性异质结,通过使用真空插入和偶极校正消除了来自不期望界面的人工效应。我们发现,对于非极性、Ga极性和Al极性界面,未应变价带偏移(VBO)分别为0.92 eV、1.23 eV和1.09 eV。VBO的变化可以从界面处形变和偶极势的差异来解释。此外,考虑自发极化的影响,极性VBO相对于非极性VBO的额外能量偏移为0.33 eV。