Investigation of GaN-based light-emitting diodes grown on vicinal sapphire substrates

GaN-based light-emitting diodes (LEDs) grown on c-plane vicinal sapphire substrates are fabricated and characterized. All the electrical characteristics demonstrate that the LED with a 0.2 degrees tilt sapphire substrate exhibits the lowest defect density while that with a 1.0 degrees tilt sapphire exhibits the highest one. At 2 mA, the enhanced output power of 23.3% indicates the substantial reduction of defect-related nonradiative recombination centers in MQW for the LED device with a 0.2 degrees-tilt sapphire. At 60 mA, the improved value is up to 45.7 %. This is primarily caused by the presence of indium quantum dots (QDs) in MQW which provides increased quantum efficiency. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim