Estimation of point defects content in bulk GaN

Abstract

The paper reveals the investigation of cathodoluminescent properties of point defects in bulk GaN sample grown by the HVPE technique. The cathodoluminescence spectra of GaN exhibit two broad luminescence bands in the blue and yellow optical ranges. The studies have shown that each of the observed luminescence bands is associated with the emission of several point defects - luminescence centers with similar spectral positions, but different decay times. The paper proposes a technique for estimation of the luminescent centers relative content. The technique is based on measuring the cathodoluminescence intensity dependence on the electron beam current density and decay times of the bands. The changes in the relative contents of point defects - luminescent centers are determined for the back and front sample regions – at the beginning of growth and near the sample surface. The excitation capture efficiency was determined for luminescence centers with the longest decay time emitting in the yellow range. It was found to be constant for different regions of the sample.