Growth, structure and optical characterization of Al-doped ZnO nanoparticle thin films

Al-doped ZnO nanoparticle thin films were prepared on glass substrate at the optimum temperature of (410 +/- 10) degrees C by spray pyrolysis technique using zinc nitrate as a precursor solution and aluminium chloride as a dopant. The dopant concentration (Al/Zn at%) was varied from 0 to 2 at%. Structural analysis of the films shows that all the films are of polycrystalline zinc oxide in nature, possessing hexagonal wurtzite structure. The films exhibit variation in peak intensities corresponding to (100), (002) and (101) reflection planes on Al-doping. The crystallite size calculated by Scherrer formula has been found to be in the range of 35-65 nm. The optical absorption study shows that the optical band gap in the Al-doped films varies in the range of 3.11 -3.22 eV. The width of localized states in the band gap estimated by the Urbach tail analysis has been found to be minimum in case of the 1 at% Al-doped zinc oxide thin film. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim