Performance Enhancement of GaN-Based Laser Diodes With Prestrained Growth

Effects of the prestrained growth of a low-In InGaN/GaN quantum well (QW) before the designated light-emitting high-In InGaN/GaN multi quantum wells (MQWs) in GaN-based laser diodes (LDs) are numerically investigated. Simulation results show that the inserted low-In InGaN/GaN QW does not remarkably change the absorption loss, and the ratio of recombination current of low-In InGaN/GaN QW over injection current is very small, especially after LD is lasing. However, it weakens the polarization fields, resulting in less tilted energy bands, and the overlap of electron-hole pairs is greatly increased, which reduces threshold carrier concentrations of MQWs, leakage current, and nonradiative recombination. The performance of LD is enhanced. Threshold current is reduced by 19%, and output power is increased by 59% at the injection current of 120 mA.