Interplay of stimulated emission and Auger-like effect in violet and blue InGaN laser diodes
Abstract
We have studied two types of InGaN laser diodes emitting at 410 and 440 nm, looking for the presence of the efficiency “droop” and its influence on the performance of these devices. By measuring the devices in two experimental geometries: a) along the resonator axis, b) perpendicularly to the cavity, we were able to conclude that the light emission process in these laser diodes operating below the threshold are governed by two mechanisms: Auger-like effect and the stimulated recombination. The competition of these two mechanisms leads to the suppression of the droop if the light is observed along the axis of the cavity. The relatively low onset of the stimulated recombination may account for the robustness of these devices against the nonradiative process (Auger-like recombination) appearing at high current densities. Additionally, we performed the characterization of InGaN light emitting diodes grown on substrates with varied In content and defect density. The results clearly demonstrate that the droop is not related in any way with the above mentioned parameters at least in the dislocation density range between 105 and 109 cm-2 and In composition range between 0.1-0.15. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
