POLARIZED SURFACE DIFFERENTIAL REFLECTIVITY AND OXYGEN-CHEMISORPTION ON INP(110) SURFACES

We present surface differential reflectivity (SDR) results on the polarization dependence of optical transitions and on the oxidation of InP(110) surfaces in the energy range between 2.0 and 4.0 eV. The surface dielectric function has been derived for the light electric vector along [110] and [001] directions. The data show two anisotropic peaks at 2.6 eV (excited with the light electric vector along the [110] direction) and 3.5 eV (excited with the light electric vector along the [001] direction) and an almost isotropic behaviour for the peak at 3.1 eV. Absorption kinetics is analyzed by following the reflectivity variation between 1 x 10(2) and 2 x 10(6) langmuirs of molecular oxygen at three selected spectral energies. Several well-defined steps of the oxidation process are clearly resolved and discussed in terms of disappearance of intrinsic surface states, creation of acceptor and donor defect states, and growth of In2O3.