Atomistic approach to the strain field in finite-sized heterostructures

The numerical code AS_LBFG_v2 developed to simulate the atomic elastic relaxation in finite-sized heterostructures is introduced. To minimize the elastic energy the L-BFGS algorithm is utilized. A user-defined initial atomic configuration, without restrictions on the shape of the matrix embedding quantum dot (QD), can be implemented in the code. By enlarging the pyramidal QD heterostructure towards mesoscopic size, the code generates a strain field distribution similar to that obtained by continuum model for weakly polar semiconductors. The strain field obtained for semi-torus, and spherical shape QDs embedded in finite-sized matrices is also presented. The dependence of the strain field on the cap thickness and the distribution of misfit dislocations in the relaxed configuration are simulated by the code.

本文介绍了一款用于模拟有限尺寸异质结构中原子弹性弛豫过程的数值代码AS_LBFG_v2。为最小化弹性势能，该代码采用了L-BFGS算法，支持用户自定义初始原子构型，且对嵌入量子点（QD）的基体形状无任何限制。通过将金字塔形量子点异质结构拓展至介观尺度，该代码可生成与弱极性半导体连续介质模型所得应变场分布一致的结果。本文还展示了有限尺寸基体中嵌入的半环面量子点与球形量子点的应变场计算结果。此外，该代码可模拟应变场对盖层厚度的依赖关系，以及弛豫构型内失配位错的分布特征。