Electrical properties of V2O5 thin films obtained by atomic layer deposition (ALD)

Abstract

Dielectric and conductivity spectra of a V₂O₅ thin film were recorded in a broad frequency range 40–1.1 × 10⁸ Hz at temperatures varying between 205 and 297 K. The V₂O₅ thin film (thickness 260 nm) was deposited on titanium substrate by atomic layer deposition (ALD). An annealing process at 500 °C in air was required to obtain crystallized V₂O₅. All the data are presented in the form of complex resistivity diagrams which have been analyzed in relation to characterizations with scanning electron microscopy (SEM) and X-ray diffraction (XRD). These diagrams show the existence of relaxations due to interfacial polarization phenomena (grain boundary polarization) within the sample, which permits the determination of the dc-conductivity of the grain (monocrystal). A dielectric relaxation is found, attributed to non-adiabatic small polaron hopping. The corresponding relaxation frequency is thermally activated with an activation energy of 0.14 eV. The experimental results enabled us to determine the drift mobility of the small polarons, i.e.μ_D = 1.84 × 10⁻² cm² V⁻¹ s⁻¹ at room temperature.