Characterization of the Solid State Properties of Anodic Oxides on Ta-Nb Alloys as a Function of the Anodizing Conditions

Abstract

Tantalum oxide, niobium oxide and Ta-Nb containing mixed oxides were grown by anodizing sputter-deposited Ta xNb (1-x) alloys with 0 ≤ x ≤ 1. A photoelectrochemical investigation was performed in order to estimate the band gap values of the oxides as a function of their composition as well as to estimate their flat band potential. Differential capacitance, C, curves were recorded for all the investigated oxides in a wide range of electrode potential and for several frequencies of the alternative signal. The dependence of C on the applied potential and a.c. frequency was interpreted on the basis of amorphous semiconductor Schottky barrier, and allowed to estimate the dielectric constant of the investigated oxides