Raman scattering study of residual strain in GaAs/InP heterostructures

Abstract
A Raman spectroscopy study on highly mismatched GaAs layers with thickness ranging from 15 nm to 6.6 μm and grown by metal-organic vapor-phase epitaxy on InP (001) substrates, is reported. Both LO and TO GaAs phonons have been observed in backscattering and Brewster geometries. In the thinnest samples large frequency red shifts with respect to the bulk are measured indicating large residual tensile strains. The Raman measurements agree with x-ray-diffraction measurements and confirm that layers thinner than 30 nm exhibit a 3D growth mechanism as suggested by transmission electron microscopy investigations.