Reduced surface sidewall recombination and diffusion in quantum-dot lasers

We examine the surface recombination rate in quantum-dot semiconductor lasers and determine the diffusion length (1.0 μm) and, for the first time, provide a value for surface recombination velocity (5×10
⁴
cm/s) in quantum-dot material. As a result of strong carrier confinement in the dots, these values are much lower than in comparable quantum-well lasers (5×10
⁵
cm/s and 5 μm, respectively) allowing the creation of narrow (2-3 μm wide) lasers with comparable threshold currents to those of broad area devices.