Surface and Electrical Characterization of Non-Stoichiometric Semiconducting Thin-Film Coatings Based on Ti-Co Mixed Oxides Obtained by Gas Impulse Magnetron Sputtering

Abstract

This article presents a detailed investigation of non-stoichiometric (Ti,Co)Ox thin films prepared using the Gas Impulse Magnetron Sputtering (GIMS) technique. The films were prepared with various Co contents (3 at.%, 19 at.%, 44 at.%, and 60 at.%) and characterized for their material composition, microstructure, and electrical properties. The films exhibited an ohmic behavior with linear current-voltage (I-V) characteristics, and their resistivity values ranged from approximately 10−3 to 104 Ω·cm. The highest resistivity was observed in the film with 3 at.% Co content. Thermoelectric measurements revealed that all of the prepared films displayed n-type semiconducting properties, with the Seebeck coefficient (S) tending close to zero. The resistivity of the films decreased as the temperature increased, affirming their semiconducting nature. The activation energy (Ea) values, determined using the Arrhenius formula, ranged from 0.0058 eV to 0.267 eV, with the highest Ea observed for films containing 3 at.% Co. Additionally, the films’ surface topography and microstructure were examined through Atomic Force Microscopy (AFM) and optical profiler techniques. The results showed that the films had smooth, crack-free surfaces with remarkable homogeneity. The surface diversification decreased with the increase in cobalt in the (Ti,Co)Ox films.