Effects of GaN substrates on InAlGaN quaternary UV LEDs

Abstract

InAlGaN quaternary ultraviolet (UV) light emitting diodes (LEDs) on GaN substrates with low dislocation density and on GaN templates consisting of n-GaN on sapphire substrates were fabricated, and characteristics of the LEDs were compared. A UV LED on a GaN substrate showed considerably higher output power than that on a GaN template and no saturation even at the injection current of 500 mA. The output power was 1.1 mW with emission wavelength of 351 nm at the injection current of 100 mA, and increased linearly until about the injection current of 200 mA, reaching 3.8 mW at the injection current of 500 mA. Effects of GaN substrates on InAlGaN UV LEDs were revealed by cathodeluminescence images and current-voltage characteristics.