Design of electron blocking layer and its influence on the radial hole transport in GaN-based vertical cavity surface emitting laser diodes

The radial transport behavior of holes and the lateral insulation confinement of carriers in GaN-based vertical cavity surface emitting lasers (VCSELs) are investigated by modifying the design of the electron blocking layer (EBL). The calculation results indicate that the increased efficiency of hole injection into the current aperture region is the primary factor contributing to the improved laser output power observed with higher EBL doping concentrations. The energy band diagrams show that an increased EBL doping concentration can reduce the band bending, thereby affecting hole transport pathways. A new composite EBL structure is proposed, which can further decrease the band bending in the EBL region, resulting in an enhanced hole transport capability toward the center of the current aperture. Therefore, the radiative recombination rate in quantum wells is improved by enhancing the coupling between the carriers and the central optical field. This research offers insight into the structural design of high-performance GaN-based VCSELs.