GaN(100)表面结构的第一性原理计算  

First-principle study on GaN(100) surface structure

作　　者：李拥华[1] 徐彭寿[1] 潘海滨[1] 徐法强[1] 谢长坤[1] 

机构地区：[1]中国科学技术大学国家同步辐射实验室,合肥230029

出　　处：《物理学报》2005年第1期317-322,共6页Acta Physica Sinica

基　　金：中国科学院知识创新工程资助的课题~~

摘　　要：用全势缀加平面波加局域轨道 (APW +lo)的方法计算了六方GaN及其非极性 ( 10 10 )表面的原子及电子结构 .计算出的六方GaN晶体结构参数 :晶格常数和体积弹性模量与实验值符合得很好 .用平板超原胞模型来计算GaN( 10 10 )表面的原子与电子结构 ,结果表明表面顶层原子发生键长收缩并扭转的弛豫特性 .表面阳离子向体内移动 ,趋向于sp2 平面构形 ;而表面阴离子向体外移动 ,趋向于锥形的p3构形 .弛豫后 ,表面实现由半金属性向半导体性的转变 .并且 ,表面电荷发生大的转移 ,参与表面键的重新杂化 ,使得表面原子的离子性减弱共价性增强 。We have calculated the atomic and electronic structures of the non-polar surface of GaN (1010) by employing the full potential augmented plan wave and local orbital method (APW + lo). The calculated lattice constant and bulk modulus of zinc-blend GaN crystal are in excellent agreement with the experimental data. Using the slab and supercell model, we find that the surface is characterized by a top-layer bond-lenth-contracting rotation relaxation. The surface Ga atom moves inward with 0.014nm and form a planar sp(2)-like bonding with its three N neighbors. While the surface N atom moves outward with 0.013nm and tends to a taper p(3)-like bonding with its three Ga neighbors. The surface layer rotation angle is 8.5degrees. From the calculated results of the desity of states of GaN (1010) surface we find that the surface relaxation induces the transformation from semi-metallic to semiconducting characteristic. Furthermore, it is also shown that the surface charges have a large transfer, and the surface bonds have a rehybridization, which makes the ionicity reduce and the covalence increase, we believe that it causes the surface bond shortening and rotating.

关 键 词：原子 表面 键长 弛豫 平面波 电子结构 晶格常数 体内 体外 转移 

分 类 号：O471[理学—半导体物理]