Investigation of the strain distribution of GaN/AlN Wurtzite structure material self-organized truncated pyramid shaped quantum dot

Abstract

Based on the three-dimension finite element approach, we Investigated the strain field distributions of GaN/AlN self-organized quantum dot. The truncated hexagonal pyramid shaped quantum dots that have been found in experiment was adopted as the physical model in our simulation. The material used in this paper is wurtzite phase structure and there are five independent elastic constants. In dealing with the lattice mismatch, we employed a three-dimension anisotropic pseudo-thermal expansion. We compared the calculated results with that calculated by Green's function theory, which lots of assumption is adopted, and proved the correctness of our results. The strain distributions of the equal strain surface three-dimension contour plots of the six strain components are given. In the final, the anisotropic characteristics of the GaN/AlN quantum dot material is discussed, the results showed that the position of the elastic strain energy density minimum was just on top of the buried quantum dot and have little influence on the thickness of the cap layer. So the anisotropy has no obviously influence on the vertical alignment of post-growth for the next layer of quantum dots. Our model did not adopt the assumptions used in the Green's function approach, so better reliability and accuracy results are expected.