An influence of deposition temperature on structural, optical and electrical properties of sprayed ZnO thin films of identical thickness

Abstract Nanocrystalline ZnO thin films were deposited at different temperatures ( T s  = 325 °C–500 °C) by intermittent spray pyrolysis technique. The thickness (300 ± 10 nm) independent effect of T s on physical properties was explored. X-Ray diffraction analysis revealed the growth of wurtzite type polycrystalline ZnO films with dominant c -axis orientation along [002] direction. The crystallite size increased (31 nm–60 nm) and optical band-gap energy decreased (3.272 eV–3.242 eV) due to rise in T s . Scanning electron microscopic analysis of films deposited at 450 °C confirmed uniform growth of vertically aligned ZnO nanorods. The films deposited at higher T s demonstrated increased hydrophobic behavior. These films exhibited high transmittance (>91%), low dark resistivity (∼10 −2  Ω-cm), superior figure of merit (∼10 −3  Ω −1 ) and low sheet resistance (∼10 2  Ω/□). The charge carrier concentration (η -/cm 3 ) and mobility (μ – cm 2 V −1 s −1 ) are primarily governed by crystallinity, grain boundary passivation and oxygen desorption effects.