Crystal Structures and their phase stabilities of mesoscopic order and disorder phases in III2VI3 compound semiconductor containint structural vacancy

III_2VI_3化合物半导体的基本结构之一是锌的共混结构，并且III_2VI_3化合物的三分之一的阳离子位是空位。在785 ℃退火的Ga_2 Te_3晶体中发现了长周期的超结构，它具有周期为每10个{111}面的三维平面缺陷。根据图像对比度计算和几何考虑，发现周期性平面缺陷的起源是聚集在1/3阳离子亚晶格中的结构空位。也就是说，虽然Se亚晶格是完全的面心立方结构，但晶体由四面体和八面体组成，四面体和八面体的外表面都是{111}空位面，空位面包围的区域结构是正常的混锌结构，在这种结构中，空位含量在晶胞尺度上是不均匀的，而在介观区域是均匀的，有数万个空位存在。该相不再是简单的有序相，而是介观或介观有序相。介观化合物半导体的主要稳定机制是尽可能多地形成四重VI族原子。但对于空位面周期性排列的原因，却没有给出明确的解释。

One of the basic structures of III2VI3 compound semiconductors is zincblend structure and one third of cation sites of III2VI3 compounds are vacant. We have found a long period super structure appears in the Ga2Te3 annealed at 785ﾟC having 3 dimensional planer defects with periodicity of every ten {111} planes. On the basis of image contrast calculation and geometrical consideration, the origin of the periodic planer defects is found to be agregated structural vacancies which locate in 1/3 of cation sublattice. That is, although Se sublattice is perfect FCC,the crystal consists of tetrahedraons anf octahedrans whose outer surfaces are all {111} vacancy planres, and structure of the area which are surrounded by vacancy planes is nomal zincblend structure.In this structure, vacancy content is imhpmogenious on the unit cell scale, but homogenious on the mesoscopic area in which several ten thousands of exsists. The phase is no longer simple order phase and is recognized by mesoscopic or mesoscopic order phase. The main stabilization mechanism of the mesoscopic compound semiconductor is to form four fold group VI atoms as much as possible. For the question why the vacancy planes periodically aline, however, clear explanation is not given.