Dynamical growth processes of group IV semiconducting films on the polar surfaces of compound semiconductors as assessed by RHEED rocking curve

近年来，第四族半导体(111)表面的生长方式引起了人们的极大兴趣。然而，关于III-V化合物半导体的{111}极面生长方式的研究报道很少。本工作的目的是(I)确定InSb{111}A，B-(2*2)原子配位的表面法向分量；(Ii)用反射高能电子衍射(RHEED)研究在这些表面上α-Sn膜的动态生长过程。主要结果如下：(1)通过基于动力学衍射理论的RHEED摇摆曲线的定量分析，确定了InSb{111}A、B-(2*2)分别具有空位翘曲结构和Sb-三聚体结构的表面法向原子坐标。InSb(111)A-(2*2)原子的表面具有较大的向内弛豫(-0.8)。另一方面，对InSb(111)B-(2*2)的分析表明，Sb-三聚体位于衬底Sb原子上方-2.8的高度，并且显著的弛豫发生在Sb-三聚体下面的亚表面区域。(Ii)用RHEED强度振荡技术研究了锡在InSb{111}A，B上生长的表面。在整个薄膜厚度范围内，表面形成双层晶格。然而，在这两个系统中，最外表面层的几何形状有很大的不同：InSb(111)A上的生长表面与晶格形成的周期相同，而在InSb(111)B上，在Sn6毫升以下和高于6毫升时，分别在单层和双层上出现了光滑的表面。表面几何形状的单层周期变化归因于生长表面上的Sb偏析。

Recently, growth mode of the (111) surface of group-IV semiconductors has generated great interest. However, little work has been reported on the growth fashion on the {111} polar surfaces of III-V compound semiconductors. The purpose of this work is (i) to determine the surface normal components of atomic coordinated of InSb {111} A,B- (2*2) and (ii) to study dynamical growth processes of alpha-Sn films on these surfaces by using reflection high-energy electron diffraction (RHEED). Main results are given as follows :(i) By the quantitative analysis of RHEED rocking curves based on the dynamical diffraction theory, we have determined the surface normal atomic coordinates of the InSb {111} A,B- (2*2) surfaces which have the In-vacancy bucking structure and the Sb-trimer structure, respectively. The surface In atoms of InSb (111) A- (2*2) exhibit a large inward relaxation (-0.8). The analysis of InSb (111) B- (2*2), on the other hand, has revealed that the Sb-trimer is located at a height of -2.8 above the substrate Sb atoms, and that the prominent relaxation occurs in the subsurface region beneath the Sb-trimer.(ii) Surfaces of Sn growing on InSb {111} A,B has been studied with use of the RHEED intensity oscillation technique. The surfaces proceed in the formation of a bilayred lattice in the whole range of film thickness. However, the geometry of the outermost surface layr is quite different in both systems : The growing surface on the InSb (111) A smoothens with the same period as the lattice formation, whereas on InSb (111) B,below and above 6 ML of Sn, smooth surfaces emerge every period of monolayr and bilayr, respectively. The monolayr-period change in surface geometry is attributed to Sb segregation on the growing surface.