Stability of electric characteristics of Au films on Si(111)5.55 × 5.55-Cu surface exposed to oxygen

Dependence of the surface electric conductivity of the layered Au/Si(111)5.55 × 5.55-Cu structure on the thickness of Au film and exposure in oxygen has been studied using low-energy electron diffraction, Auger electron spectroscopy, and four-point-probe conductivity measurements. The samples were obtained by depositing Au (1–5 monolayers, ML) in vacuum at room temperature onto preliminary prepared Si(111)5.55 × 5.55-Cu surface, after which the structure was kept in oxygen (to a total exposure varied within 0–14000 L) at room temperature. It is established that the increasing oxygen exposure of both the initial and Si(111)5.55 × 5.55-Cu surface and that coated with gold to 1–3 ML leads to a significant decrease in the surface conductivity of samples. In contrast, the conductivity of samples coated with more than 3 ML of gold remains almost unchanged, which is explained by the fact that a continuous Au film is formed in this case on the Si(111)5.55 × 5.55-Cu surface.