Effect of strain-compensation in stacked 1.3μm InAs∕GaAs quantum dot active regions grown by metalorganic chemical vapor deposition

Abstract

We have introduced tensile layers embedded in a $\mathrm{GaAs}$ matrix to compensate compressive strain in stacked $1.3\mu \mathrm{m}$ $\mathrm{InAs}$ quantum dot (QD) active regions. The effects of the strain compensation are systematically investigated in five-stack and ten-stack QD structures where we have inserted ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}\mathrm{P}$ ($x=0.30$ or 0.36) layers. High-resolution x-ray diffraction spectra quantify the overall strain in each sample and indicate $>35\%$ strain reduction can be accomplished. Both atomic force and transmission electron microscope images confirm that strain compensation improves material crystallinity and QD uniformity. With aggressive strain compensation, room temperature QD photoluminescence intensity is significantly increased demonstrating a reduced defect density.