Physical property exploration of highly oriented V2O5 thin films prepared by electron beam evaporation

Abstract

Highly oriented vanadium pentoxide (V₂O₅) thin films were grown by electron beam (EB) evaporation on glass substrates at 473 K. V₂O₅ thin films were coated with various thicknesses (≈800–1200 nm) by varying the distance from the source and substrates. The influence of film thickness on its physical properties was deeply studied by various characterization techniques. XRD studies were performed to investigate the structural confirmation and preferential lattice orientation of EB evaporated films. The Voigt profile method was used to estimate the microstructural parameters and to elaborately discuss its dependency on film thickness. SEM micrographs perceived that the prepared films were nearly homogeneous with densely packed morphology. AFM topographical images depicted the nanograins on the surface of the films. Raman spectra confirmed the formation of the α-V₂O₅ polymorph without secondary phase formation. From the optical absorption data, the indirect optical band gap ‘E_g’ was found to be 2.36 eV for V₂O₅ thin film with higher thickness. Optical constants such as refractive index (n), extinction coefficient (k), optical conductivity (σ) and dielectric constants (ε) were evaluated using an approximation protocol developed from well recognized procedures using the data obtained from the UV-Vis spectroscopic technique. The luminescence property variations were observed by photoluminescence (PL) spectroscopy and it has elucidated the role of film thickness in the EB evaporated V₂O₅ films. The Hall mobility and carrier density were found to increase with film thickness.