Efficiency and Droop Improvement in GaN-Based High-Voltage Light-Emitting Diodes

Abstract—The efficiency and electrical characteristics of GaN-based high-voltage light-emitting diodes (HV-LEDs) are in-vestigated in detail. The spatial distribution of light output and simulation results showed that 100-V HV-LED with smaller mi-crochips had superior current spreading. As a result, under 1-W operation, the luminous efficiency of 100-V HV-LED with smaller microchips was enhanced by 7.8 % compared to that of 50-V HV-LED, while the efficiency droop behaviors were reduced from 28 % in 50-V HV-LED to 25.8 % in 100-V HV-LED. Moreover, smaller microchips exhibited lower series resistance and forward voltage, leading to higher wall-plug efficiency. Index Terms—Current spreading, efficiency droop, high volt-age, light-emitting diodes. I