Influence of anisotropic in-plane strain on critical point resonances in reflectance difference data

The sharp resonances in reflectance difference spectroscopy (RDS) data at t he critical points of the dielectric function of bulk semiconductors have b een assigned to surface-bulk transitions. photon localization, or optical t ransitions from bound dimer states to excited dimer states. For the case of ZnTe, CdTe, and ZnSe, we present experimental data indicating that a uniax ial in-plane stress component induces sharp resonances at these critical po ints by lifting the degeneracy of the optical transitions at the A and Gamm a points due to the resulting anisotropic strain. Even small stresses of ab out 1-5 MPa, or strains on the order of 1 X 10(-5) can be detected with RDS . (C) 2001 American Vacuum Society.