Size-dependent Electroluminescence Characteristics of GaN-based UV-A μLEDs

Abstract

This study investigates the size-dependent electrical and optical characteristics of GaN-based ultraviolet-A (UV-A) micro light emitting diodes (μLEDs). As the device size decreases, reverse leakage current significantly increases, while forward current density decreases due to Shockley–Read–Hall recombination at side wall trap sites, which leads to a higher ideality factor in smaller devices. This electrical degradation strongly correlates with optical performance, as smaller μLEDs exhibit lower light output at the same current density and a shift in peak external quantum efficiency (EQE) toward higher current densities. Notably, reducing the device size by a factor of 100 leads to a30% drop in peak EQE and a nine fold increase in the required current density. These findings underscore the need for effective suppression or elimination of sidewall defects to enable high efficiency UV-A μLED display applications. © 2025, John Wiley and Sons Inc. All rights reserved.