High-efficiency 350 nm-band quaternary InAlGaN-based UV-LED on GaN/sapphire template

We hive demonstrated high-efficiency ultraviolet (UV) light-emitting diode (LED) with emission wavelength at 349 nm using quaternary InAlGaN multiple-quantum-well (MQW) fabricated on a GaN/sapphire template. The threading dislocation density of the GaN/sapphire template was approximately 1x10(9)cm(-2). The maximum UV output power obtained was as high as 4.1 mW with an injection current of 160 mA under room temperature (RT) CW operation. The maximum external quantum efficiency (EQE) was 1.02% with an injection current of 60 mA, which is higher than the EQE obtained for a 350 nm-band AlGaN-based QW LED fabricated on GaN substrate. From these result, we confirmed the advantage of the use of quaternary InAlGaN for 350 nm-band UV emitters in comparison with the use of AlGaN. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.