Effect of precursor volume on chemically sprayed V2O5 thin films for acetaldehyde detection

Abstract

Abstract V2O5 has attracted much attention because of its multivalent layered structure, high catalytic and electrical properties. It is also potential candidate for chemiresistive gas sensor application. V2O5 films are deposited using chemical spray pyrolysis technique at a substrate temperature of 300 °C by varying volume of the precursor. X-ray diffraction studies confirm that deposited thin films are polycrystalline nature with orthorhombic phase. The predominant peak, which has the maximum intensity, has appeared along (001) direction and it is considered as preferred orientation. The crystallite size is determined using Scherrer's formula and it is found to increase from 19.2 to 26.4 nm with the increase of precursor volume. The surface morphology of the films is explained using SEM and it has appeared as fibre-like morphology at the volume of 30 mL precursor. Chemical stoichiometry of the V2O5 films is analyzed using EDX and the spectra consist of vanadium and oxygen atoms only. Layered structured and polycrystalline behaviour of the deposited thin films is studied using micro-Raman spectroscopy. Optical properties are investigated using UV–Visible spectroscopy and the optical band gap is measured using Tauc plot and it is found increase from 2.28 to 3.33eV as the volume of the precursor is enhanced from 20 mL to 40 mL. The mobility, concentration of charge carriers and resistivity of vanadium pentoxide thin films prepared at various precursor volumes determined using Van der Pauw Hall system. Gas sensing investigations have been carried out using the static liquid distribution method. The selectivity of the film towards various volatile organic vapours is determined.