Improvement Of The Droop Efficiency In Ingan-Based Light-Emitting Diodes By Growing On Gan Substrate

The high quality GaN substrates were fabricated by hydride vapor phase epitaxy (HVPE). The threading dislocation densities (TDDs) in the InGaN/GaN multiplequantum- well light-emitting diodes (LEDs) on high quality GaN substrate was substantially reduced, leading to a significant reduction in an improved droop effect at high current density. Compared to the same devices grown on Al2O3, these LEDs showed the enhancement in output power and reduction in droop. In this study, we demonstrate the optical and electrical properties of LEDs grown on Al2O3 and GaN substrate. The LEDs on GaN substrate outperformed the LEDs on Al2O3 at forward voltage, output power, and external quantum efficiency (EQE) for 1.5 %, 40 %, and 15 % enhanced, respectively. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim