Performance Enhancement of a-Plane Light-Emitting Diodes Using InGaN/GaN Superlattices

Abstract

We have fabricated a-plane light-emitting diodes (LEDs) with inserted InGaN/GaN superlattices. The structural characteristics and device performance of a-plane light-emitting diodes with/without superlattices were also identified. Transmission electron microscope (TEM) images revealed that the threading dislocation (TD) density for the sample using superlattices was reduced from 3 x 10(10) cm(-2) down to similar to 9 x 10(9) cm(-2). The electroluminescence (EL) intensity of the sample with InGaN/GaN superlattices was enhanced by a factor of 3.42 times to that of the conventional sample without InGaN/GaN superlattices. Furthermore, we observed that the polarization degree of a-plane LEDs with superlattices (56.3%) was much higher than that without superlattices (27.4%). A series of experiments demonstrated that the feasibility of using InGaN/GaN superlattices for the TD reduction and the improvement of luminescence performance in a-plane III-nitride devices. (C) 2009 The Japan Society of Applied Physics