Increasing Light Extraction Efficiency for UV LEDs with a Low Coverage p-GaN Hole Injection Layer

We report on the use of ultrathin low-coverage p-GaN hole injection islands on the top surface to improve the light extraction in UV LEDs, resulting in world-record UVB AlGaN UV LEDs emitting at 300 and 310 nm. With the optimization of the p-GaN island density, size, thickness, and doping, we demonstrated a 300 nm emitting device with a peak continuous wave (CW) external quantum efficiency (EQE) of 18.9%, a peak CW wall plug efficiency (WPE) of 16.8%, and a CW EQE of 8.8% at 20 A/cm2, and a 310 nm emitting device with a peak CW EQE of 20.3%, a peak CW WPE of 15.4%, and a CW EQE of 10.9% at 20 A/cm2.