Investigation on interface-related defects by photoluminescence of cubic (Al)GaN/AlN multi-quantum wells structures

Cubic (Al)GaN/AlN multiple quantum wells were grown by plasma assisted molecular beam epitaxy with three different configurations at interfaces. We employ temperature-dependent photoluminescence to characterize interface imperfections. Our results show shallow localization states responsible to photocarrier localization at low temperatures. The potential fluctuation model estimates localization energies in the order of few meV. We investigated a single GaN/AlN, double GaN/AlN quantum wells, and a double quantum well with an additional AlGaN spacer layer as a step between the wells. The introduction of AlN and AlGaN interlayer reduces the effect of localization and indicates better interfaces for the QW structures based on cubic GaN.