Formation of an Active Electronic Barrier at Al/Semiconductor Interfaces: A Novel Approach in Corrosion Prevention

Abstract

Abstract Aluminum surfaces exhibit significantly improved corrosion protection when coated with suitable semiconductor/insulator thin films. These coatings, generally realized in metal-semiconductor (MS) or metal-insulator-semiconductor (MIS) structural configurations, lead to an interfacial electric field that acts as an effective built-in electronic barrier. This active barrier significantly impedes electron transfer from the aluminum surface to foreign species that cause oxidation by accepting the electrons. Anodic polarization data on numerous samples fabricated in both MS [e.g., Al-indium tin oxide (ITO)] and MIS (e.g., Al-SiO2-ITO) configurations have demonstrated the protective nature of the built-in active electronic barrier. The electronic barrier heights have been shown to increase with (1) the presence of a thin (20- to 100-A) SiO2 layer at the metal/semiconductor interface and (2) the energy gap of ITO, which depends on the indium content. A comparison of these results with data obtained on pl...