Exciton dynamics at a single dislocation in GaN probed by picosecond time-resolved cathodoluminescence

We investigate the dynamics of donor bound excitons (D degrees X-A) at T = 10K around an isolated single edge dislocation in homoepitaxial GaN, using a picosecond time-resolved cathodoluminescence (TR-CL) setup with high temporal and spatial resolutions. An similar to 1.3 meV dipole-like energy shift of D degrees X-A is observed around the dislocation, induced by the local strain fields. By simultaneously recording the variations of both the exciton lifetime and the CL intensity across the dislocation, we directly assess the dynamics of excitons around the defect. Our observations are well reproduced by a diffusion model. It allows us to deduce an exciton diffusion length of similar to 24 nm as well as an effective area of the dislocation with a radius of similar to 95 nm, where the recombination can be regarded as entirely non-radiative. (C) 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)