IN-SITU MONITORING BY SPECTROSCOPIC ELLIPSOMETRY IN ZNSE CRYSTAL-GROWTH BY MOLECULAR-BEAM EPITAXY

We report the first in-situ monitoring by spectroscopic ellipsometry ( SE) of the heteroepitaxial growth of ZnSe on GaAs by molecular beam ep itaxy. In a series of experiments wherein ZnSe was grown on GaAs subst rates or epilayers having various reconstructed GaAs surfaces, the tra jectories of (PSI, DELTA) and dielectric function spectra were measure d and analyzed. It was found that the As-rich c(4 x 4), the As-deficie nt (6 x 4) and the Ga-rich (4 x 2) reconstructed GaAs surfaces resulte d in two-dimensional (layer-by-layer), pseudo-two-dimensional, and thr ee-dimensional growth of ZnSe, respectively, and it was also found tha t the dielectric function of the as-grown ZnSe is quite different from that of the air-exposed ZnSe epilayer.