The effects of AlGaN quantum barriers on carrier flow in deep ultraviolet nanowire laser diode

Abstract

Aluminium (Al) composition is a critical parameter of performance for deep ultraviolet (DUV) AlGaN devices. In multiple-quantum-wells (MQW) nanowire laser diode, quantum barriers play an important role in carriers’ flow (electrons, holes). In this work, the impact of composition, and the thickness of AlGaN-based quantum barriers is being studied. The study suggests that by properly increasing Al composition of quantum barriers, the height of the conduction band barrier decreases, which enhances electron leakage from MQW, while increasing the height of the valance band barrier, which, in turn, suppresses hole injection efficiency toward MQW. Such variations in band height greatly affect opto-electronic characteristics and performance of AlGaN nanowire. Furthermore, the study also suggests that quantum barrier thickness has much influence on DUV nanowire performance. The decrease in thickness of quantum barriers has little effect on confinement of the optical field, but significant effect on optical emitted power. It is found that by decreasing the thickness of quantum barriers, optical emitted power along with stimulated recombination rate is reduced. Contrastingly, as the thickness of quantum barriers increases, hole injection efficiency gets enhanced while electron leakage from MQW gets reduced. The above observations suggest that the higher the thickness of quantum barriers, the better the carriers’ flow toward MQW and hence, the performance is improved.