ELECTRONIC-STRUCTURE OF METAL SAPPHIRE INTERFACES

We have investigated metal‐Al2O3 bonding by AES (Auger electron spectroscopy), EELS (energy electron loss spectroscopy) and XPS (x‐ray photoelectron spectroscopy). The metal–alumina interfaces were formed by in situ vapour deposition and we studied the early stages of metal condensation for Pd, Ni, Cr and Zn at room temperature on well‐defined (0001) and (1012) sapphire surfaces. Depending on the treatment, these surfaces exhibit different electronic structures. Upon increasing the metal coverage, new electronic features appear, which point out the role of surface defects (oxygen vacancies, dangling bonds, etc.) during the formation of the first metal monolayer. Copyright © 1990 John Wiley & Sons Ltd.