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

Nanocrystalline ZnO thin films were deposited at different temperatures (T-s = 325 degrees C-500 degrees C) by intermittent spray pyrolysis technique. The thickness (300 +/- 10 nm) independent effect of Ts 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 degrees 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 (similar to 10(-2) Omega-cm), superior figure of merit (similar to 10(-3) Omega(-1)) and low sheet resistance (similar to 10(2) Omega/square). The charge carrier concentration (eta -/cm(3)) and mobility (mu - cm(2)V(-1)s(-1)) are primarily governed by crystallinity, grain boundary passivation and oxygen desorption effects. (C) 2013 Elsevier B. V. All rights reserved.