CHARACTERIZATION OF THE CRYSTALLOGRAPHIC STRUCTURE OF MGO THIN-FILMS BY ISS ON THE BASIS OF TRAJECTORY-DEPENDENT NEUTRALIZATION

The structure of thin oxide films formed on the Mg(0001) surface has been a controversial subject. Both MgO(100)-like non-polar surfaces and MgO(111)-like polar surfaces have been proposed on the basis of LEED and work function measurements. In an attempt to resolve this controversy, the structure of the topmost layer of a MgO thin film was investigated by ISS, along with that of the (100) face of a MgO(100) single crystal. The angular dependence of the ISS spectra from the MgO(100) surface was found to be governed by an ion neutralization process. Based on this neutralization mechanism, a semi-empirical model was developed to simulate the ISS results from the thin film surface. The simulation demonstrated that the oxide layers on the Mg(0001) surface cannot be represented as MgO(100) domains, and that this surface is more likely covered by oxygen, as in the polar structure. © 1990.