Si组分对SiGe量子点形状演化的影响

研究了自组织生长SiGe岛（量子点）中Si组分对形状演化的影响.采用UHV/CVD方法生长了 不同Si组分的SiGe岛，用AFM对其形状和尺寸分布进行了分析，实验结果表明SiGe岛从金字 塔形向圆顶形转变的临界体积随Si组分的增大而增大.通过对量子点能量的应变能项进行修正，解释了量子点中Si组分对形状演化的影响.在特定的工艺条件下得到了单模尺寸分布的 金字塔和圆顶形量子点.结果表明，通过调节SiGe岛中的Si组分，可以实现对SiGe岛形状和 尺寸的控制.关键词：自组织生长SiGe岛Si组分临界体积

Influence of Si concentration on the evolution of shape and size of self-assembled Ge islands

The influence of Si concentration on the shape transition of self-assembled SiGe islands was investigated. SiGe islands with different Si concentrations were grown by UHV/CVD. The topography and size distribution of islands were characterized by atomic force microscopy. The results show that the critical volume increases with Si concentration, at which the islands change from pyramids to domes. A modified model was established and used to explain the influence of Si concentration on the shape transition by introducing the revised strain energy term depending on Si concentration. Dome shaped as well as pyramid shaped uni modal SiGe islands were grown under suitable conditions. This research indicates that the shape and size of the self assembled ialnds can be controlled more accurately by adjusting Si concentration.