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Effect of molar concentration on the optical and surface properties of CdO thin film deposited by spray pyrolysis

M. M. ISLAM1, J. PODDER1,* , M. R. ISLAM1

Affiliation

  1. Department of Physics, Bangladesh University of Engineering & Technology, Dhaka-1000, Bangladesh

Abstract

Cadmium oxide (CdO) thin films have been deposited onto glass substrates from different molar concentration of cadmium acetate precursor solution using a simple spray pyrolysis technique. The surface morphology, structural and optical properties of the films has been characterized by Scanning Electron Microscopy (SEM) attached with an EDX, X-ray diffraction study and UV spectroscopy. From EDX data, atomic weight % of Cadmium and Oxygen are found to be 41.11% and 58.89% respectively. The SEM micrographs of as-deposited film show uniform deposition over the substrate. On annealing, the surface roughness increases and reveals sprayed particles (atoms) are adsorbed onto the glass substrate to form clusters as the primary stage of nucleation. At higher annealing temperature growing nuclei come into contact to form island stage and appears as spheroid shape. The crystal structure of the as deposited and annealed films were found to be polycrystalline with cubic structure and the lattice constant is a=4.65Å. The absorption coefficient is obtained in the order of 104 cm−1. For different molar concentrations (0.1M ~ 0.5M), the direct band gap is found to be in the range 2.40 ~2.53 eV and indirect band gap in the range 1.70~ 2.14 eV. The band gap energies depend on molar concentration of solution.

Keywords

Spray pyrolysis, CdO, Molarity, Optical band gap.

Citation

M. M. ISLAM, J. PODDER, M. R. ISLAM, Effect of molar concentration on the optical and surface properties of CdO thin film deposited by spray pyrolysis, Optoelectronics and Advanced Materials - Rapid Communications, 4, 7, July 2010, pp.968-972 (2010).

Submitted at: March 1, 2010

Accepted at: July 14, 2010