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 epitaxy. In a series of experiments wherein ZnSe was grown on GaAs substrates or epilayers having various reconstructed GaAs surfaces, the trajectories of (PSI, DELTA) and dielectric function spectra were measured and analyzed. It was found that the As-rich c(4 x 4), the As-deficient (6 x 4) and the Ga-rich (4 x 2) reconstructed GaAs surfaces resulted in two-dimensional (layer-by-layer), pseudo-two-dimensional, and three-dimensional growth of ZnSe, respectively, and it was also found that the dielectric function of the as-grown ZnSe is quite different from that of the air-exposed ZnSe epilayer.