Effect of the multiarray chip structure on the optical performance of GaN-based light emitting diodes

Abstract

Multiarray chip (MAC) light-emitting diodes (LEDs) are introduced as an alternative approach to decrease the junction temperature, leading to reduced efficiency droop in high-power GaN-based LEDs. Despite using the same LED epiwafer, the authors found that the efficiency droop decreased on reducing the chip size from 1 × 1 to 8 × 8 MAC-LED cells. Although electroluminescence (EL) intensities of all MAC-LEDs demonstrated almost comparable results below an injection current of 100 mA, the efficiency droop of MAC-LEDs reduced when the current density was 10 A/cm2 owing to decrease in the satellite chip size. By using the forward voltage method, the junction temperature of MAC-LED gradually decreased on increasing the number of satellite chips in the MAC-LED. Based on these results, the authors suggest that the MAC-LED would be effective in improving the heat-dissipating rate, resulting in the reduction of efficiency droop without significantly decreasing the EL intensity.