The Amorphous Semiconductor Schottky Barrier Approach to Study the Electronic Properties of Anodic Films on Ti

Abstract

A detailed study of the electronic properties of thin (<20 nm) anodic TiO 2 potentiostatically grown on titanium in two different solutions is presented. The results show that the nature of the anodizing solution affects the electronic properties of the anodic film and, more specifically, the density of electronic states (DOS) distribution. Different DOS were derived from the experimental data analyzed according to the theory of amorphous semiconductor (a-SC) Schottky barrier. It is shown that the usual non-linear and frequency dependent Mott-Schottky plots are in agreement with expected theoretical behavior of a-SC Schottky barrier.

A Generalized Semiempirical Approach to the Modeling of the Optical Band Gap of Ternary Al-(Ga, Nb, Ta, W) Oxides Containing Different Alumina Polymorphs

“…In previous works, ,,,,,, we suggested as a possible rationale for these findings a different degree of amorphousness as a function of the different anodizing parameters. Our suggestion was in agreement with the model of electronic density of state (DOS) in amorphous semiconductors described in the classical Mott–Davis book showing how a different degree of lattice disorder affects the DOS in the vicinity of the conduction and valence band edges .…”

“…It has been shown for different amorphous passive films on valve metals (Al, Ta, Nb, W, Ti, etc.) and their alloys ,, that during the anodization process, both anodizing current and final voltage, despite the fact the final anodizing voltage is kept below the onset of the electrical breakdown process, affect sensibly the measured optical band gap values of the amorphous anodic film. , Usually, amorphous thicker films, grown at a constant growth rate, or films grown at lower growth rates display lower optical band gap values with respect to thinner films or films grown at higher anodizing rates. ,, …”

Passivity of Spring Steels with Compressive Residual Stress

“…The authors of this study point out that the Mott-Schottky analysis has limitations as applied to passive films, because a passive film is not a well-defined semiconductor. Therefore, several assumptions are employed commonly and the results of the analysis are interpreted with care [53][54][55]. In particular, the quantitative property derived from the Mott-Schottky analysis (i.e., the donor density in this study) cannot be directly compared with that of other alloys.…”

Photocorrosion of n‐ and p‐Type Semiconducting Oxide‐Covered Metals: Case Studies of Anodized Titanium and Copper

“…[ 15 ] However, for strongly disordered oxides which are typical for thin oxide films in corrosion, the flat band potential is typically not very well defined and thus difficult to determine directly from Mott–Schottky analysis. [ 3,16 ] This difficulty thus contributes to the difficulties of building up consistent band diagrams for corroding metals with semiconducting oxides.…”

“…[13] band potential is typically not very well defined and thus difficult to determine directly from Mott-Schottky analysis. [3,16] This difficulty thus contributes to the difficulties of building up consistent band diagrams for corroding metals with semiconducting oxides. One issue which is especially severe in applications is the frequently poorly defined or even changing Fermi level of the electrolyte.…”