有限元法分析不同形状量子点的应变能及弛豫度变化

Analysis of strain energy and relaxation degree in different-shaped quantum dots using finite element method

利用有限元方法研究了不同形状量子点的应变能量分布和弛豫度随着高宽比变化的规律.分析了量子点间距和量子点形状对量子点应变弛豫的影响,定量地讨论了量子点的弛豫度与量子点形状之间的关系.计算结果表明,在不考虑表面能的情况下,当量子点高宽比增加时,弛豫度上升,并且发现平顶金字塔形量子点最先达到稳定;岛间距增大时,量子点内应变能下降,其中立方体形量子点应变能下降最快.研究表明,量子点的弛豫度可以成为控制量子点成岛形状的重要依据.

The distribution of strain energy and the strain relaxation degree as functions of the aspect ratio in different-shaped quantum dots were studied using finite element method. The impact on strain relaxation, originating from the shape and the inter-island distance, was also quantitatively analyzed. The results indicate that when ignoring the surface energy, the relaxation degree increases with the increase of the aspect ratio regardless of the shape, among which the truncated pyramid quantum dots tend to become steady earlier than others. With the increase of the inter-island distance, the strain energy in the dots decreases, especially in the cubic dots. A good reference is provided by the relaxation degree for controlling the shape of quantum dots.