Capture kinetics at deep-level electron traps in GaN-based laser diode

Two deep-level electron traps, El at E-C - 0.23 eV and E2 at E-C - 0.55 eV, have been revealed by means of deep-level transient spectroscopy (DLTS) in a GaN-based laser-diode heterostructure grown by metalorganic vapour-phase epitaxy on a bulk GaN substrate. The two traps represent different electron capture behaviours. The El trap, which exhibits the logarithmic capture kinetics and the DLTS-line shape characteristic of band-like electron states, is attributed to the core states of threading dislocations in a p-type layer of the structure. In contrast, the E2 trap, being the most prominent deep-level electron trap in GaN layers, displays the exponential capture kinetics and is assigned to isolated point defects, likely the nitrogen antisite defect.