Effect of Co-doping on the properties of Zn1 − xCoxO films deposited by spray pyrolysis

Thin films of Zn1 − xCoxO have shown potential application in the field of dilute magnetic semiconductors. Zn1 − xCoxO films were prepared on glass substrates at a temperature of 350 °C over the composition range, 0–12%. The structure, composition, optical and magnetic properties of as-grown Zn1 − xCoxO films were studied using appropriate techniques. The X-ray diffraction spectra showed a predominant (002) reflection corresponding to the hexagonal wurtzite structure. No changes in the preferred orientation with composition were observed. The films showed hexagonal shaped grains that were uniformly distributed and the evaluated grain size varied in the range, 20–40 nm. The films prepared at x = 10% showed good crystallinity and surface morphology. The X-ray photoelectron spectroscopy studies indicated uniform composition across the thickness of the layers, and a shift in the peak positions of Zn2p3/2, Zn2p1/2 and O1s was observed with the increase of Co-doping content. The films exhibited an optical transmittance > 75%, and the energy band gap varied in the range 3.37–3.18 eV with the change of Co-doping. The films also exhibited magnetic behavior at low temperatures. The results were reported and discussed.