Low resistance distributed polarization doped p-AlGaN layer for 265 nm LEDs operating at very high current densities

Abstract Ultraviolet-C light-emitting diodes (UVC-LEDs) with low resistance distributed polarization doped (DPD) p-type AlGaN layers are investigated. The UV-transparent DPD p-AlGaN layers provide high hole carrier densities in high aluminum mole fraction UVC-LEDs emitting near 265 nm. The influence of the DPD p-AlGaN layer thickness (50–320 nm) on the electrical and optical characteristics of UVC-LEDs is systematically evaluated. Despite the large variation of the DPD layer thickness, the voltages at 50 mA of the devices remained largely unchanged, demonstrating that the highly conductive p-type DPD layers do not significantly contribute to the series resistance. Nevertheless, UVC-LEDs with thinner DPD p-AlGaN layers exhibited higher output powers but also increased leakage currents. Capacitance–voltage (C–V) measurements show that the hole concentration increases from 6 × 10 17 cm −3 to 4 × 10 18 cm −3 with decreasing p-AlGaN DPD thickness from 320 nm to 50 nm consistent with simulation results. Under pulsed operation, UVC-LEDs were able to operate at very high current densities of up to 90 kA cm −2 without breaking down. The findings of this study establish DPD p-AlGaN layers as a promising approach for high-performance UVC-LEDs, laser diodes and electronic devices.