Published online by Cambridge University Press: 15 February 2011
Using a photoelastic modulator in the optical-bridge configuration, the reflectivity difference was obtained for GaAs and ZnSe (100) surfaces over the photon energy range from 1.5 eV to 6 eV with various azimuthal orientations of the surface. The RD data of GaAs (100) are similar to previously reported data. The RD data of ZnSe (100) are larger by an order of magnitude than those of GaAs (100), possibly due to the larger ionicity of Zn and Se atoms. The distinctive critical point structures and interference patterns shown in the RD spectra of ZnSe (100) suggest that the data, if obtained in real time, could be used to determine the alloy composition, thickness and temperature during growth. The RD data are analyzed using models proposed by Aspnes. The results indicate that the major contribution to the RD spectra of ZnSe (100) are from the surface local field unlike the RD spectra of GaAs (110), whose major contribution is from the bulk spatial distribution.