Quantum dot lasers based on a stacked and strain-compensated active region grown by metal-organic chemical vapor deposition

We demonstrate an InAs∕GaAs quantum dot (QD) laser based on a strain-compensated, three-stack active region. Each layer of the stacked QD active region contains a thin GaP (Δao=−3.8%) tensile layer embedded in a GaAs matrix to partially compensate the compressive strain of the InAs (Δao=7%) QD layer. The optimized GaP thickness is ∼4MLs and results in a 36% reduction of compressive strain in our device structure. Atomic force microscope images, room-temperature photoluminescence, and x-ray diffraction confirm that strain compensation improves both structural and optical device properties. Room-temperature ground state lasing at λ=1.249μm, Jth=550A∕cm2 has been demonstrated.