Tan Chih-Shan, Huang Michael H
Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu 300093, Taiwan.
Department of Chemistry, National Tsing Hua University, Hsinchu 300044, Taiwan.
Phys Chem Chem Phys. 2022 Apr 20;24(16):9135-9140. doi: 10.1039/d2cp00100d.
Density functional theory (DFT) calculations on a tunable number of GaN (0001) planes give an invariant band structure, density of states (DOS) diagram, and band gap of the GaN unit cell. Dissimilar band structures and DOS diagrams are obtained for 1, 3, 5, 7, and 9 layers of GaN (101̄0) planes, but the same band structure as that of the (0001) plane returns for 2, 4, 6, and 8 (101̄0) planes. Furthermore, 1 to 4 layers of GaN (101̄1) planes exhibit dissimilar band structures, but the GaN unit cell band structure is obtained for 5 (101̄1) planes. While there are no changes to the Ga-N bond length and bond geometry for the (0001) planes, the (101̄0) planes present bond length variation and bond distortion with odd numbers of layers. Bond length and bond direction deviations are also obtained for 1 to 4 (101̄1) planes. These results suggest that slight structural deviations may be present near the GaN surface to produce facet-dependent properties, and such atomic position deviations in the surface layer can be observed in various semiconductors.
对可调数量的GaN(0001)平面进行密度泛函理论(DFT)计算，得到了GaN晶胞不变的能带结构、态密度(DOS)图和带隙。对于1、3、5、7和9层GaN(101̄0)平面，得到了不同的能带结构和DOS图，但对于2、4、6和8层(101̄0)平面，恢复了与(0001)平面相同的能带结构。此外，1至4层GaN(101̄1)平面呈现出不同的能带结构，但对于5层(101̄1)平面，得到了GaN晶胞的能带结构。虽然(0001)平面的Ga-N键长和键几何结构没有变化，但(101̄0)平面在奇数层时呈现键长变化和键畸变。对于1至4层(101̄1)平面，也得到了键长和键方向偏差。这些结果表明，GaN表面附近可能存在轻微的结构偏差，以产生与晶面相关的性质，并且在各种半导体中都可以观察到表面层中的这种原子位置偏差。
