Zinc Oxide (ZnO) and Aluminium doped ZnO (AZO) thin films were deposited on soda lime glass by Metal Organic Chemical Vapour deposition technique (MOCVD), using prepared compound mixtures of Zinc Acetate di-hydrate (Zn(CH 3 COO) 2 •2H 2 O; ZAD) and Aluminium Acetyl-Acetonate (Al(C 5 H 7 0 2) 3 ; AAA) precursors at a temperature of 420˚C. Effects of the varying mole percent concentrations of AAA precursor additives on the Al dopant concentrations in ZnO were systematically studied. The observations were made via investigations carried out on the morphological, optical, electrical and compositional properties of the deposited thin films. The thin films morphology was found to be strongly dependent on the varying concentration of AAA in the precursor mixtures. The average optical transmittance of the thin films in the uv-visible region was over 85% except 5 mol.% Al. While the energy band gaps were found to be in range of 3.27-3.36 eV. There is a blue-shift of the energy band edge observed between 0 and 5 mol.% AAA, which may be due to Burstein-Moss' band gap widening effect and an opposing band gap renormalization effect at 10 mol.% AAA along with an extra band gap stabilization effect (Roth's effect) at 15 mol.% AAA in rather quasi-sinusoidal or anomalous behaviour. The optical transmittance and electrical conductivity of ZnO were enhanced with addition of Al dopants. The RBS confirm the presence of Al, Zn and O, and evidence that Al dopants were successfully incorporated into the ZnO.

Chromium (Cr) doped Zinc oxide ZnO thin films were deposited onto glass substrates by Metal Organic Chemical Vapour Deposition (MOCVD) technique with varying dopant concentration at a temperature of 420˚C. The effect of the chromium concentration on morphological, structural, optical, electrical and gas sensing properties of the films were investigated. The scanning electron microscopy results revealed that the Cr concentration has great influence on the crystallinity, surface smoothness and grain size. X-ray diffraction (XRD) studies shows that films were polycrystalline in nature and grown as a hexagonal wurtzite structure. A direct optical band energy gap of 3.32 to 3.10 eV was obtained from the optical measurements. The transmission was found to decrease with increasing Cr doping concentration. Rutherford Backscattering Spectroscopy (RBS) analysis also demonstrates that Cr ions are substitutionally incorporated into ZnO. I-V characteristic of the film shows a resistivity ranges from 1.134 × 10 −2 Ω cm to 1.24 × 10 −2 Ω cm at room temperature. The gas sensing response of the films were enhanced with incorporation of Cr as a dopant with optimum operating temperature around 200˚C.