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.

Lateral characteristics improvements of DBR laser diode with tapered Bragg grating

“…The vertical structure of wafer is grown on N-GaAs substrate. [14,15] A 10.4-nm-thick In 0.27 Ga 0.82 As/GaAs single quantum well is placed as active region into 400-nm thick waveguide. The Al 0.3 Ga 0.7 As is grown as the cladding, with the n-dopant being silicon and the p-dopant zinc.…”

Performance enhancement of ultraviolet-C AlGaN laser diode

“…These leaked electrons may then recombine with the holes in the p-region, which will overcome the injection of holes in active region [ 12 ]. The recent proposed designs have overcome these challenges, which include the superlattice design of last quantum barrier [ 13 ], quaternary superlattice last barrier [ 14 ], double tapered EBL [ 15 ], step doping in waveguide and cladding layer [ 16 ], compositional Al-grading of silicon-doped layers [ 17 ], AlGaN-based polarization doped layers without impurity doping [ 18 ], step-graded quantum barriers with graded EBL [ 19 ] and inverse trapezoidal EBL [ 20 ].…”

Optimization of AlGaN-Based Deep Ultraviolet Laser Diodes with Graded Rectangular Superlattice Electron Blocking Layer and Graded Trapezoidal Superlattice Hole Blocking Layer

“…The use of electron blocking layer (EBL) and hole blocking layer (HBL) can reduce carrier leakage, increase recombination rate, and optimize the performance of devices [15]. To solve the above problems, Xing et al proposed inverted trapezoidal EBL to reduce the electron leakage in the p-type region [16], Wang et al proposed graded EBL to improve the radiative recombination rate in the quantum wells (QWs) of DUV-LDs [17], and Yi et al proposed the specially designed AlGaN superlattice EBL and HBL based on rectangular superlattice (RSL) EBL and HBL [18]; then, they design AlGaN grade superlattice EBL and HBL to improve the performance of UV light-emitting diodes [19]. Though the use of the superlattice structure has achieved progress, there is still room for improvement.…”