Optical and electrical properties of GaN micron-scale light-emitting diode

The III-nitride-based micron-scale light-emitting device (LED) could suppress the current crowding effect and increase the light extraction from micro-cavity. The uniform and high light extraction efficiency could be achieved with micro-LEDs. No reliable micro-LEDs or micro-LEDs array could be fabricated due to the etching damage and p-type ohmic contact stability. The single micro-LEDs with mesa-structure were fabricated with device size changed from 15 to 5 mu m. The 3 mu m single micro-LEDs with ring-structure were fabricated by lithography technology in diffraction mode. In tow current injection (0-2 V), the tunneling-recombination current through the shallow state was increasing while the device size was shrinking. In middle current injection (2-2.6 V), the tunneling recombination through the deep gap state was also increasing due to the etching damage. Under high-current injection (> 2.6 V), the current transport was described by drift-diffusion-recombination model and Schottky-like p-type contact. The high fluctuation of the series resistance and high ideality factor was observed in micro-LEDs. The post-treatment with hot KOH solution was used to reduce the etching damage. After post-treatment, the etching damage was reduced with mesa-structure. The micro-ring device was destroyed after post-treatment. No power saturation with 15 x 15 um(2) micro-LEDs were observed under high-current density injection with electroluminescence measurement. (c) 2007 Elsevier Ltd. All rights reserved.