The optical constants of pure and CO-covered copper films

Abstract

Copper films in the thickness range 60–300 Å were prepared by evaporation under ultrahigh vacuum conditions and were investigated ellipsometrically. The optical constants obtained for the pure films agree well with data given in the literature. With increasing CO coverage a phase retardation which tended to a saturation value in the monolayer coverage region was observed. Simultaneously the ratio of amplitudes increased or decreased according to whether the wavelength was above or below a certain value. These results can be qualitatively interpreted with the aid of a layer model of the adsorbed CO molecules. A more detailed evaluation, however, leads to discrepancies which must be traced back to the real structure of the films under investigation.