Efficiency droop enhancement in AlGaN deep ultraviolet light-emitting diodes by making whole barriers but the bottom Mg doped. (September 2016) - Sun, Jie
Abstract: Ultra violet light-emitting diodes (UVLEDs) with different types of Mg-doped barriers have been studied. The energy band diagrams, internal quantum efficiency, total output power and radiative recombination rate are investigated by APSYS software. The simulation results show that the UVLED with only a p-doped top barrier get little enhancement comparing to the conventional one, on the contrary the structure with p-doping in all but the bottom barriers has a much better optical and electrical properties due to enhancement of the holes' injection and the electrons' confinement. The efficiency droop is significantly alleviated and the light output power is greatly enhanced. To avoid forming a PN junction by the bottom barrier and the n-AlGaN in the proposed structure, therefore, the bottom barrier isn't p-doped. Then structures with different hole densities in the Mg-doped barriers have been studied numerically and that confirmed the best. Highlights: Making all but the bottom barriers Mg-doped can alleviate the efficiency droop and enhance the rad recombination. Then the best holes density of the p-doped barriers has been confirmed. AlGaN-based UVLED with three different p-doped barriers are compared in detail. P-doping in the top barrier could not improve the performance and it has little change comparing to the old structure. The root of efficiency droop has been explored.