Photoreflectance study of gallium arsenide grown on Si

Low-temperature linear polarized photoreflectance is used to study the stress and its release in thick GaAs grown on Si. We find that the GaAs layer is mainly composed of two regions with two kinds of stress, biaxial and uniaxial. Four features, two from each region due to the split valence band, are observed. Their polarization selection rules enable us to distinguish the nature of the strain as well as the nature of the transitions.