InAs/GaAs quantum dot structures covered by InGaAs strain reducing layer characterized by photomodulated reflectance

Abstract

Optical properties of metalorganic vapor phase epitaxy grown InAs quantum dots in GaAs covered by thin In x Ga 1− x As strain reducing layer were studied by photomodulated reflectance and photoluminescence spectroscopy. Results show that the increasing In content in the strain reducing layer shifts the luminescence of quantum dots from 1.25 to 1.46 μm and narrows the photoluminescence linewidth. To interpret photoluminescence data, we developed a simulation model of our quantum dot structure, which was calibrated using results of atomic force microscopy, photoluminescence and photoreflectance measurements. Simulations have shown that the strong photoluminescence red shift is caused both by the change of the band structure and the height of quantum dots which is significantly increasing when the In content in the strain reducing layer grows.