Improvement of radiative recombination rate in deep ultraviolet laser diodes with step-like quantum barrier and aluminum-content graded electron blocking layer*

Abstract

The design of the active region structures, including the modifications of structures of the quantum barrier (QB) and electron blocking layer (EBL), in the deep ultraviolet (DUV) AlGaN laser diode (LD) is investigated numerically with the Crosslight software. The analyses focus on electron and hole injection efficiency, electron leakage, hole diffusion, and radiative recombination rate. Compared with the reference QB structure, the step-like QB structure provides high radiative recombination and maximum output power. Subsequently, a comparative study is conducted on the performance characteristics with four different EBLs. For the EBL with different Al mole fraction layers, the higher Al-content AlGaN EBL layer is located closely to the active region, leading the electron current leakage to lower, the carrier injection efficiency to increase, and the radiative recombination rate to improve.