Strain recovery in partially relaxed In0.2Ga0.8As/GaAs single quantum wells with increasing GaAs cap layer thickness

Abstract

The effect of cap layer thickness on residual strain in partially relaxed, 250 AA thick In0.2Ga0.8As/GaAs single quantum well structures was examined by photoluminescence, transmission electron microscopy and high-resolution x-ray diffraction. When the cap layer thickness increased from 50 to 5000 AA, the residual strain increased from 0.88% to the misfit value of 1.4%. As a consequence the cap layer thickness should be taken as a parameter, along with misfit and growth temperature, to determine critical layer thickness in lattice-mismatched single quantum well structures.