Numerical Investigation on the Enhanced Performance of N-Polar AlGaN-Based Ultraviolet Light-Emitting Diodes With Superlattice p-Type Doping

Abstract

N-polar AlxGa1−xN-based 365-nm ultraviolet (UV) light-emitting diodes (LEDs) with a hole-supplier layer composed of p-type Al0.2Ga0.8N/GaN superlattice (SL) doping or bulk doping structures are numerically investigated over Ga-polar UV-LEDs counterpart. The simulation results demonstrate that N-polar LEDs are favorable in mitigating the negative effect of the polarization-induced electric field. Thus, it exhibits superiority in promoting carriers confinement capability and suppressing electrons overflow over Ga-polar. As a result, the internal quantum efficiency, light output power, and electroluminescence intensity are significantly improved. In addition, both Ga-polar and N-polar devices exhibit the increased hole concentrations and higher radiative recombination rate within quantum wells after adopting SL p-doping structure. From the simulated energy band diagrams, the polarization-induced higher acceptor ionization rates at the heterostructure interfaces are observed. Evidently, the UV-LEDs based on N-polar SL p-doping structure are very effective to improve its performance, which is promising in achieving high-performance UV-LEDs of the future fabrication.