Influence of stacking on optical characteristics of GaN/AlN self-organized quantum dots

摘要

The effect of stacking on the optical properties of self-organized GaN/AlN quantum dots (QDs) grown by plasma-assisted molecular beam epitaxy was investigated by photoluminescence (PL), PL excitation (PLE), and cathodoluminescence (CL) spectroscopic techniques. With an increase in the number of the GaN QDs stacking layer, we observed a red shift in the main QD PL peaks. A Stokes-like shift was observed between PL emission and PLE absorption edge for all the samples. From the depth-resolved CL of a 200-period GaN QD sample, we observed that the main QD CL emission peak energy position does not change much, while the higher-energy side CL peak around ～ 3.7 eV shows a variation of its peak position with the accelerating voltage probably due to the change in either distribution of QD size/shape or wetting layer properties during the growth of multiple stacking of GaN QDs.