Modelling oxide thin films

Three simulation methodologies have been employed to investigate the growth, nucleation, and structure of oxides supported on oxide substrates, these are atom-by-atom deposition, layer-by-layer deposition and finally amorphisation of a structure followed by recrystallisation. The materials which have been investigated include the rocksalt-structured oxides; MgO, CaO, SrO, and BaO, the perovskite structured SrTiO3 and also fluorite structured CeO2 and ZrO2. The work has shown that the substrate influences critically the structure of the supported thin film by determining the nature and interactions of defects, dislocations and grain-boundaries, as well as influencing the interfacial ion densities and various epitaxial relationships. In addition, graphical techniques have been employed to show the three-dimensional atomistic structure of each structural and epitaxial feature. Moreover, by considering large simulation cell sizes (approaching the mesoscale, 18 nm square), it has been possible to accommodate the synergistic interactions between neighbouring structural features, which can lead to changes in their basic structure. We also show that the particular surface termination of the substrate can influence the structure (and tentatively, the critical thickness) of the supported film through the example of SrO and TiO2 terminated faces of a SrTiO3(001) substrate. © 2002 Taylor & Francis Ltd.