Milliwatt Power 350 nm-band Quaternary InAlGaN UV-LEDs on GaN Substrates

Abstract

We have demonstrated milliwatt output power from quaternary InAlGaN-based multi-quantum-well (MQW) ultraviolet (UV) light-emitting diodes (LEDs) with an emission wavelengths of 350–360 nm. GaN substrates were used in order to reduce the density of threading dislocations. By examining a cathode luminescence (CL) image, we confirmed that the threading dislocation density of the quaternary InAlGaN MQW layer was reduced to as little as 1 × 107 cm–2 by using GaN substrate. A significant increase in the UV output power was achieved by increasing the Al content of the p-AlxGa1–xN electron blocking layer up to 28%. As a result, the maximum UV output power obtained was as high as 3.8 mW at 351 nm and 6.3 mW at 358 nm under room temperature (RT) CW operation. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)