The dependence of the strain effects on the CdTe layer thicknesses in [formula omitted] heterostructures

Abstract

Photoluminescence (PL), spectroscopic ellipsometry and photoreflectance (PR) measurements on CdTe GaAs strained heterostructure grown by molecular beam epitaxy were carried out to investigate the effects on the strain and the lattice parameter due to the CdTe epitaxial layer thickness in a CdTe GaAs heterostructure. While the PL peaks of the acceptor bound excitons shift toward the higher-energy side with increasing film thickness, resulting from a shift in the energy of the heavy holes, the absorption peaks appearing within the PR spectra due to the band edge shift toward the lower-energy side with increasing film thickness, resulting from the small splitting energy between the first heavy hole and the light hole. Compressive strains exist in CdTe layers thinner than 2 μm. As the strain increases, the values of the critical-point energy-shifts increase linearly. These results indicate that the strains in the CdTe layers grown on GaAs substrates are strongly dependent on the CdTe layer thickness.