Effect of surface treatment on the performances of vertical-structured GaN-based LEDs with electroplating metallic substrate

Vertical-structured GaN-based light-emitting diodes with metallic substrate (VM-LEDs) were fabricated employing nickel electroplating and patterned laser lift-off (LLO) techniques, as well as the effect of the cathode surface-treatment on the performance characteristics of the LEDs was investigated. Experimental results show that the light extraction efficiency of VM-LEDs could be significantly enhanced by surface roughening using C12/He/CH4 plasma and KOH etching; in addition, the n-pad contact characteristics could also be improved by chemical treatment using HF and HCl solutions. As compared to that of conventional blue-LEDs with lateral structure, a light output power (Lop) of 2.12 (2.32) times at 20 (80) mA with a forward operating voltage of 3.2 (3.65) V has been achieved