A red-emitting micrometer scale LED with external quantum efficiency >8%

Abstract

Significant efforts are being put into the development of efficient micrometer-scale light emitting diodes (LEDs) for future display technologies due to their marked benefits over existing displays. To date, however, the efficiency of microLED devices remains significantly lower than that of conventional broad-area devices. The deterioration in device performance with smaller device size has been linked to the plasma damage induced on mesa sidewalls during device fabrication. Here, we studied bottom-up red-emitting nanowire LEDs with different Mg doping levels in the p-GaN layer. The resulting sub-micron LED devices show a distinct improvement in efficiency with increasing Mg dopant incorporation. Through optimization of the doping, we measured an external quantum efficiency of ∼8.3% and a wall-plug efficiency of ∼4.6%, at a current density of ∼1 A/cm2, for a red-emitting sub-micrometer scale LED operating at >630 nm. This study highlights the importance of p-doping in microLEDs for attaining high efficiency performance in nanostructure-based devices.