REFLECTANCE-DIFFERENCE STUDIES OF INTERFACE-FORMATION AND INITIAL-GROWTH PROCESSES IN ZNSE GAAS(001) HETEROEPITAXY/

In situ reflectance-difference studies of initial stages of ZnSe growt h on GaAs(001) surfaces are reported. ZnSe layers with thicknesses les s than 4 nm were grown by molecular beam epitaxy in both layer-by-laye r and island-growth modes. It is found that the reflectance-difference spectra for this thickness range are clearly dependent on ZnSe thickn ess as well as on the growth mode, This observation indicates that the surface electronic structure develops with thickness and in a manner sensitive to the mid-or long-range order of the surface. The interface -induced peak at 2.8 eV, intensity of which is correlated with the ext ent of the interfacial Ga-Se bond formation, is pinned during the cour se of growth, which indicates that atomic rearrangement or mixing at t he interface is minimal once several monolayers of ZnSe are deposited on GaAs. (C) 1997 American Vacuum Society.