ZnO films fabricated by chemical bath deposition from zinc nitrate and ammonium citrate tribasic solution

Zinc oxide (ZnO) films were prepared on glass substrates by chemical bath deposition at 50 degrees C. A solution of zinc nitrate, ammonium citrate tribasic and sodium hydroxide was used, and various deposition conditions were investigated. The optimal ratio of [Zn(NO3)(2)]:[(NH4)(3)C6H5O7]: [NaOH] was 10.0:4.0:4.3, and the optimal annealing temperature was 400 degrees C. X-ray diffraction patterns showed that the annealed films prepared at the optimal ratio have a wurtzite structure. Scanning electron micrograph showed that the film consists of nanoparticles with a size of several decade nanometers. Transmittance spectra showed high optical absorption below 380 nm and transmittance over 80% in the range of 400-900 nm. The optical band gap of the film annealed at 400 degrees C was 3.26 eV, and the dark electrical resistivity was with an order of 10(3) Omega cm at room temperature. (c) 2008 Elsevier B.V. All rights reserved.