NEAR-BREWSTER ELLIPSOMETRIC DETERMINATION OF REFRACTIVE-INDEXES FOR SUBMONOLAYER ADSORBATES - APPLICATION TO ANTIMONY ON SILICON (111)

Measurements of ellipsometric parameters are used to follow adsorption and desorption of antimony on silicon (111) below the monolayer coverage in an MBE UHV chamber at epitaxial temperatures. Approximations at Brewster incidence within an island model allow to determine a relation between the real and imaginary parts of the dielectric constant of the adsorbate which is independent of coverage and effective thickness. Calibrated surface density of adsorbate atoms at the monolayer leads to a determination of both its effective thickness and dielectric constant.