Self-consistent simulation and analysis of InGaN/GaN lasers

We analyze the performance of nitride Fabry-Perot laser diodes with two InGaN/GaN quantum wells. Those devices exhibit the lowest threshold current density (1.2 kA/cm²) as well as the highest output power (420 mW) reported thus far for room-temperature continuous-wave operation of nitride lasers. The active region includes an AlGaN electron stopper layer. It is sandwiched between GaN separate confinement layers and superlattice AlGaN/GaN cladding layers. The thickness of the n-side cladding layer was increased from 600 nm to 1200 nm to reduce the penetration of the laser light into the GaN substrate. In order to better understand performance limitations, we study this device using advanced laser simulation. The laser model self-consistently combines band structure and gain calculations with two-dimensional simulations of waveguiding, carrier transport, and heat flux. It considers carrier drift and diffusion including thermionic emission at hetero-boundaries. This allows for a study of vertical carrier leakage, lateral current spreading, and defect recombination. The reduction of such carrier losses is important to achieve less self-heating and higher output power