Influence of InGaN waveguide on injection efficiency in III-nitride laser diodes

Abstract

The influence of using InGaN waveguides on blue laser diodes was theoretically studied using 1D drift diffusion model and 2D optical mode calculation. Despite of the known effect of increased confinement of an optical mode, especially for long wavelengths, an unexpected influence on the efficiency of carrier injection into the active region is discussed. It is found that InGaN-AlGaN interface is crucial to achieving high injection efficiency. A numerical model is created, which describes the influence of InGaN waveguide and Mg doping of electron blocking layer on basic properties of laser diodes. It is found that an increase of injection efficiency allows to reduce the doping level in an electron blocking layer and take advantage of decreased optical losses.

GaN-based distributed feedback laser diodes grown on Si

“…This phenomenon was more severe in GaN-on-Si LD due to a relatively high TD density (∼6 × 10 8 cm −2 ) resulted from the huge mismatch in lattice constant between GaN and Si. Moreover, the non-optimized upper WG and EBL also cause additional carrier accumulation in the upper WG regime, which causes undesired recombination, leading to a low injection efficiency [37,38]. All of these would be responsible for the relatively low injection efficiency and high threshold current density.…”