Investigation of the Properties of Ca-doped TiO2 Thin Films Formed by e-beam Evaporation

Abstract

Titanium dioxide is considered as one of the most important materials due to its unique dielectric, electrochemical, photocatalytic and optical properties. These properties can be altered by introducing particular amount of dopants. In this work, Ca-doped titanium dioxide was formed by electron beam deposition method and the structural and electrical properties were investigated. For the evaluation of the structural properties the formed thin ceramic films were studied by X-ray diffraction (XRD), energy dispersive spectrometry (EDS) and scanning electron microscopy (SEM). Electrical properties were investigated by impedance spectroscopy. It was found that when the concentration of Ca dopants increases the crystallites size increases as well and follows Vegard's law. The impedance measurements show that the Ca-doping decreased the total conductivity of the formed thin films. The total conductivity varies from 2.7 S/cm in pure TiO2 to 4 × 10-4 S/cm in 2.5% Ca doped TiO2 at 800°C under wet reducing conditions and from 5.4 × 10-4 S/cm in pure TiO2 to 3.4 × 10-5 S/cm in 0.5% Ca doped TiO2 at 800°C under wet oxidizing conditions.