Optical transitions and radiative lifetime in GaN/AlN self-organized quantum dots

Abstract

We present a theoretical study of the optical matrix elements and radiative lifetime for the ground state optical transitions in GaN/AlN quantum dots (QD). An efficient plane-wave expansion method is used to calculate the energy levels, wave functions, and optical matrix elements in the framework of a multiband k⋅p model taking account of the three-dimensional strain and built-in electric field distributions for QDs with a hexagonal truncated-pyramid shape. We demonstrate that the built-in electric field determines the energy spectrum of GaN/AlN QDs and leads to a dramatic decrease in the optical matrix element with increasing QD size. As a result, the radiative lifetime for the ground state optical transition increases strongly with QD size. The theoretical results obtained are in good agreement with available experimental data.