Design Considerations for GaN-Based Blue Laser Diodes With InGaN Upper Waveguide Layer

Effects of an inserted InGaN interlayer between active region and p-AlGaN electron blocking layer on electrical and optical characteristics of GaN-based blue laser diodes are numerically investigated. It is found that the inserted InGaN interlayer reduces the barrier height for hole injection into multiple quantum wells. Moreover, it is found that the background electron concentration of the undoped InGaN plays a critical role in the LD performance. A background electron concentration higher than 1 × 10¹⁷ cm^-3 may induce undesired electron-hole recombination in this layer. In addition, we have calculated the dependences of optical confinement factor and internal absorption loss (IAL) on location, In composition, and thickness of the InGaN layer. A significant increase in OCF and a decrease in IAL are obtained by inserting the InGaN layer.