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本文利用高分辨透射电子显微技术及高分辨像几何相位分析技术,对分子束外延方法生长在GaSb(001)面上的InAs/GaSbⅡ型超晶格材料进行了界面显微结构和解理特征的研究。众所周知,InAs和GaSb都是立方硫化锌结构,具有平行于{110}面的六组完全解理面,然而,本工作中发现InAs/GaSb超晶格的解理面发生改变,平行于{111}面解理,并在InAs/GaSb界面处发生扭折,呈现锯齿状解理边缘。而在InAs盖帽层即非超晶格区域内,解理面依然平行于{110}面。通过建立超晶胞模型与计算分析表明,在超晶胞中由于共格应力的对称性降低,(110)面的电中性发生改变,导致解理面从电中性的{110}面转变为面网密度最大的{111}面。界面两侧应力分布分析结果表明,锯齿状{111}解理边缘是Ga-As型界面与In-Sb型界面所受应力作用不同的结果。
In this paper, the characteristics of the interface microstructure and cleavage of InAs / GaSb Ⅱ superlattice grown on GaSb (001) surface by molecular beam epitaxy are studied by using high-resolution transmission electron microscopy and high-resolution image geometric phase analysis the study. It is well known that both InAs and GaSb are cubic zinc sulfide structures with six complete cleavage planes parallel to the {110} plane. However, cleavage planes of the InAs / GaSb superlattice have been found to change in this work, parallel to {111 } Surface cleavage, and kinks at the InAs / GaSb interface, showing jagged cleavage edges. In the InAs capping layer, ie, the non-superlattice region, the cleaved plane is still parallel to the {110} plane. Through the establishment of the supercell cell model and the calculation and analysis, it is shown that the electrical neutrality of the (110) plane changes due to the decrease of the symmetry of the coherent stress in the supercell, resulting in the transition of the cleaved plane from the electrically neutral {110} plane Is the {111} plane with the highest areal density. The results of stress distribution analysis on both sides of the interface show that the serrated {111} cleavage edge is the result of the difference in stress between the Ga-As interface and the In-Sb interface.