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 (Delta a(o)=- 3.8%) tensile layer embedded in a GaAs matrix to partially compensate the compressive strain of the InAs (Delta a(o)= 7%) QD layer. The optimized GaP thickness is similar to 4 MLs 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 lambda = 1.249 mu m, J(th) = 550 A/cm(2) has been demonstrated. (c) 2005 American Institute of Physics.