Synthesis and Characterization of Metal Organic Chemical Vapour Deposited Chromium Doped Zinc Oxide Thin Film for Gas Sensing Applications

Abstract

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.

Investigation on the impact of cobalt doping on optical, structural and magnetic properties of zinc oxide nanoparticles

“…In the quest to synthesize ZnO and transition metal doped ZnO, researchers have developed a range of techniques, including hydrothermal [17], sol-gel [18], chemical vapour deposition [19], co-precipitation [20,21], magnetron sputtering [22], ball milling [23], and many more. Each method brings its own set of advantages and limitations, making it a matter of careful consideration to determine the best approach for a given situation.…”