Improving Output Efficiency of InGaN-Based MQW Green Laser Diodes by Modulating Indium Content of Quantum Barriers and Using Composite Lower Waveguide Layers

Potential barriers between the waveguide layer and MQW active region may influence injection efficiency significantly, which is important in improving output characteristics of GaN-based green laser diodes (LDs). In this study, potential barriers and injection efficiency of LDs are investigated by simulation methods. It is found that different indium content in quantum barrier layers results in different potential barrier heights, leading to different recombination rates in upper and lower waveguide layers, and the injection efficiency can be modulated effectively. An eclectic choice of indium content can suppress recombination in two waveguide layers, improving the output characteristics of green LDs. Additionally, a composite lower waveguide layer structure is proposed to reduce the negative effect of potential barriers. High output power and low threshold current are achieved owing to the reduction in electron injection blockage and hole leakage effects.