Numerical Analysis the Strain Distribution of GaN/AlN Self-Organized Pyramid Quantum Dot

Abstract

Based on the three-dimensional finite element approach, we investigate the strain field distribution of the GaN/AlN self-organized quantum dot. The truncated hexagonal pyramid quantum dot that has been found in experiment is adopted as the physical model in our simulation. The material elastic constants parameters used in this paper are of wurtzite structure, and there are five independent elastic constants. In dealing with the lattice mismatch, we employ a three-dimensional anisotropic pseudo-thermal expansion. We compare the calculated results with that calculated by Green’s function theory, in which many assumptions are made, and prove the correctness of our results. The strain distributions of the equal strain surface three-dimensional contour plots of the six strain components are given. Finally, the anisotropic characteristics of the GaN/AlN quantum dot material are discussed, the results demonstrate that the position of the elastic strain energy density minimum position is just located above the buried quantum dot and have no influence on the thickness of the capping layer. So the anisotropy has no obvious influence on the vertical alignment of post-growth of the next layer of quantum dots. Our model does not adopt the assumptions used in the Green’s function approach, so better reliability and precision of results are expected.