Semiconducting properties of oxide films formed onto an Nb electrode in NaOH solutions

Abstract

In this paper, the results of the potentiostatic formation of homogeneous and heterogeneous, nano-crystalline passive films of Nb2O5 onto an Nb electrode in NaOH solutions of different concentrations at potentials lower than 3.0 V vs. SCE are presented. The semiconducting properties of such films were investigated by EIS measurements. After fitting the EIS results by appropriate equivalent circuits, the space charge capacitance (Csc) and space charge resistance (Rsc) of these films were determined. The donor density (Nsc), flat band potential (Efb) and thickness of the space charge layer (dsc) for such oxide films were determined from the corresponding Mott-Schottky (M-S) plots. It is shown that all oxide films were n-type semiconductors in a certain potential range.