Ultra-violet light-emitting diodes with quasi acceptor-free AlGaN polarization doping

The development and application of nitride-based light-emitting diodes (LEDs) is handicapped by the low hole conductivity of Mg-doped layers. Mg-doping becomes increasingly difficult with higher Al-content of the p-AlGaN layers as required for ultra-violet (UV) light emission. Polarization-induced hole doping of graded AlGaN was recently demonstrated as an alternative doping method. Using advanced numerical device simulation, this paper investigates the impact of polarization-doping on the internal device physics of UV-LEDs and compares the conventional Ga-face growth to the novel N-face growth direction. Various LED design options are explored to maximize the internal quantum efficiency.