Oxide semiconductors general description

At steady state and for small signal AC-polarization, semiconductors and oxide films can be represented by a resistance and a capacitor in parallel, and the electrolyte resistance in series. This is experimentally correct, but it does not help understand the system and different experiments. For a general description of oxide films, however, we must introduce four corrections ... 

Although this theory explains theoretically the experimental observations in the case of ReOj, TiO, and VO, it fails to verify the conductivity characteristics of transition metal oxides such as TiO, VO, MnO, and NiO. Band theory explains the metallic characteristics but fails to account for the electrical properties of insulators or semiconductors and metal-nonmetal transitions because of neglect of electronic correlation inherent in the one-electron approach to the problem. Although there is no universal model for description of the conductivity, magnetic and optical properties of a wide range of materials (e.g., simple and complex oxides, sulfides, phosphides), several models have been proposed (for details, see Refs. 447-453). Of these, a generally accepted one is that described by Goodenough (451). 

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