Surface texturing of p‐GaN layer for efficient GaN LED by maskless selective etching

Abstract

The maskless selective wet etching of p-GaN layer with KOH in ethylene glycol (KE) and H3PO4/H2SO4 (HH) acids was developed for the highly efficient light-emitting diodes (LEDs). The p-GaN surfaces textured by the selective wet etching process without using etch mask showed hexagonal and stripe shapes in the KE and HH solutions, respectively. The current-voltage (I-V) characteristics of the LED textured by KE and HH solutions showed improved electrical properties compared to the non-etched LED. This result could be attributed to a reduced contact resistance due to an increased contact area between the metal electrode and p-GaN layer. In addition, the light-output power of the LED textured by KE and HH solutions was improved by 29.4% and 36.8% relative to that of the non-etched LED. This result was attributed to the increase in probability of escaping photons from the LED and the reduction of surface defects by the maskless selective wet etching process. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)