Influence of tin doping onto structural, morphological, optoelectronic and impedance properties of sprayed ZnO thin films

Tin doped zinc oxide thin films are synthesized by simple chemical spray pyrolysis onto glass substrates using zinc acetate and stannic chloride precursors in an aqueous medium. The influence of tin doping onto photoelectrochemical, structural, morphological, optical, electrical and impedance properties have been investigated. Structural analysis confirms the hexagonal (wurtzite) structure of deposited films with crystal reorientation effect. SEM micrographs depict the films are rough, adherent and homogeneous with varying grain size (average grain size similar to 100-300 nm). Contact angle measurement shows that the films are hydrophilic in nature. Valence states of constituent elements in ZnO host lattice are analyzed by X-ray photoelectron spectroscopy. Direct band gap of the films decreases with tin doping up to 3.19 eV. The highest electrical conductivity (0.95 Omega (1) cm (1) and carrier concentration (8.94 x 10(17) cm (3)) and lowest mobility (6.64 cm(2) V (1) s (1)) is observed at 1.5 at.% tin doping. We studied interparticle interactions like grains, grain boundary effects using complex impedance spectroscopy. (C) 2012 Elsevier B.V. All rights reserved.