Enhanced wall-plug efficiency in monolithically integrated vertical light-emitting-diode cells based on III-nitride heterostructures

This work presents the enhancement of the wall-plug efficiency in GaN-based vertical light-emitting diodes (LEDs) by splitting into nine LED cells. The cells are monolithically integrated and connected in series to develop high-voltage vertical LEDs (HV-VLEDs). Wall-plug efficiency at an input power of 1 W for the optimum-design HV-VLEDs is improved to 43.5% from the value of 40.6%, as compared to that of conventional VLED with the same active device area. The result indicates that the HV-VLEDs with uniform current spreading improve the conversion efficiencies of VLEDs and are expected to be more beneficial in larger-chip-size and higher-power LEDs. (C) 2016 American Vacuum Society.