First principles calculation of growth dynamics and electronic properties of heterovalent burried-vacancy interfaces

通过第一性原理计算和晶体生长模拟，我们阐明了含空位的异价界面的形成动力学和电子性质如下。基于第一性原理计算，考虑了原子的四配位、表面二聚体的形成、超额电荷的键间转移、原子的长程扩散和应变效应，对晶体生长进行了蒙特卡罗模拟。(110)和(001)界面；由于电荷失配的松弛，在(110)非极性界面很容易形成原子锐利的界面。另一方面，对于(0 0 1)界面，我们发现：(1)同时供应锌和硒原子时，往往会产生引起空位缺陷和层错的Se反位；(2)最初只提供锌原子时，这种反位就消失了；(3)初始Se原子供应促进了As的蒸发…生成具有粗糙表面的气体层。所有这些结果都来自于GaAs和ZnSe化合物之间的异价态，并很好地解释了观察到的现象。ZnO/GaN(0001)界面：在生长初期，界面过剩电荷通过向表面移动来促进生长，而在生长后期，界面过剩电荷强烈地局域化在界面，对生长没有影响。所得到的接口具有类型II偏移量。空位化合物：我们发现空位层状纤锌矿In_2Se_3在吸收带隙附近具有很大的各向异性，沿(111)面沿(111)方向生长，具有松弛应变的三个周期，空位三元化合物如CdGa_2Se_4显示出较大的带隙变化，这取决于空位的有序性，拉曼散射实验很容易观察到空位的排列。阐明了InAs润湿层在GaAs(001)表面的生长促进了阳离子的混合，Si(001)的反射差谱在氧化过程中发生振荡，氯对Si(111)表面刻蚀的限制过程不是扩散而是解吸。较少

We have clarified formation dynamics and electronic properties of heterovalent vacancy-contained interfaces as follows, by using the first-principles calculations and the crystal growth simulations.1. Development of crystal growth simulator ; Monte Carlo crystal-growth simulations are developed, which are based on the first-principles calculations and take into account the four coordination of atoms, the surface dimer formation, the inter-bond transfer of excess charge, the long-range atom diffusion and the strain effects.2. ZnSe/GaAs (110) and (001) interfaces ; Due to the relaxation of charge mismatch, the atomically sharp interface is easily formed at the (110) nonpolar interface. On the other hand, we found for the (001) interface that (1) the simultaneous supply of Zn and Se atoms often produces the Se antisites which induce vacancy defects and stacking faults, (2) the initial supply of only Zn atoms extinguishes such antisites, (3) the initial supply of Se promotes the As evapola … More tion and produces GaSe layers having rough surfaces. It was proved that all these results originate from the heterovalency between GaAs and ZnSe compounds and well explain the observations.3. ZnO/GaN (0001) interfaces ; At the initial growth, the interface excess charge promotes the growth by moving to the surface, while at the later stage it is strongly localized at the interface and has no effects on the growth. The resulting interface has type-II offset.4. Vacancy compounds ; We showed that the vacancy-layered wurtzite In_2Se_3, which has large anisotropy around the absorption gap, grows along (111) with three period to relax the strain, the vacancy ternary compounds such as CdGa_2Se_4 show the large band-gap variation depending on the vacancy ordering, and the vacancy arrangement is easily observed by the Raman scattering experiments.5. Other interfaces ; We clarified that the growth of InAs wetting layers on GaAs (001) promotes cation mixing, the reflectance difference spectra of Si (001) oscillate during the oxidation, and the limitting process by Cl to etch the Si (111) surface is not the diffusion but the desorption. Less