INVESTIGATION OF AMORPHOUS OXIDE FILM-ELECTROLYTE JUNCTIONS BY AC-TECHNIQUES

Current AC (alternating current) techniques are used often to characterize the energetics at a semiconducting solid phase/electrolyte interface. For thin layers having a strongly disordered or amorphous structure (such as oxide-passive layers anodically grown on valve metals), interpretative models currently used for crystalline semiconductors may produce misleading data. A new interpretation of the admittance data, based on recent models for amorphous semiconductors (a-Sc) Schottky barriers, is presented for passive films of Nb, W and Ti. The physical bases of the model are presented as well as its advantages and disadvantages. The new theory views the solid/electrolyte interface more satisfactorily and provides information on the solid-state properties and the electronic structure of the electrode useful for interpreting the electron exchange between the solid phase and redox couples in solution.