Electronic Structure and Properties of Oxide Surfaces and Interfaces

Abstract

AbstractMany technologically-important areas rely on properties of ceramic surfaces or interfaces. Some of these properties are simply stability, e.g. resistance to dimension change, to grain-size change, or to change in coverage by a metal layer. Other properties rely on well-defined electronic features, e.g. a suitable density of surface states, of surface defects, or of response to adsorbed species. Still further surface characteristics - the precise geometric structures, the near-surface electric fields, and especially impurity segregation - can strongly influence observed behaviour.This survey emphasises the insights gained from atomistic modelling of ceramic surfaces and interfaces. The theoretical methods allow one to identify the features determining surface geometry, the degree of surface segregation by impurities, the role of the image charge and the influence of space-charge layers on intrinsic defect levels. The surface distortion affects defects like the surface Fs+ centre (electron trapped at an oxygen vacancy on an oxide) and similar colour centres. Whilst most of the results will be for oxides, parallels with semiconductor systems and the special features of metal-oxide interfaces are mentioned.