Theoretical and experimental study of structural, electronic and optical properties of cobalt-doped zinc oxide

Abstract

In this work, pristine cobalt-doped zinc oxide with the compositions ZnO, Zn_0.99Co_0.01O, and Zn_0.97Co_0.03O were prepared by the sol-gel route. Prepared samples were characterised by X-ray diffraction (XRD), UV–vis (Ultra Violet Visible Spectroscopy), and FTIR (Fourier Transform Infrared Spectroscopy). XRD pattern confirmed that the all synthesised samples have hexagonal wurtzite structure of single phase, with space group p63mc and space group number 186. UV results showed the effect of Co doping on optical properties and also showed a slightly larger energy band gap by increasing Co content. FTIR spectrum analysis gave information about the different types of functional groups in the prepared sample. The transmittance peak between 400 cm⁻¹ and 590 cm⁻¹ demonstrates a typical bond between the oxygen. The SEM image showed the surface morphology of nanoparticles and confirmed the wurtzite structure. The DMS (diluted magnetic semiconductors) have wide range applications in optoelectronics. Our results depict the enhancement in structural, optical, and electrical properties of the prepared sample through cobalt doping. In the current study, we have also evaluated the optical and electronic properties of ZnO using the first principal approach. With the addition of Co, we have observed a decrease in the ZnO band gap. Moreover, variations in the optical spectra can be linked to band structure. It has been revealed that all three compositions exhibit direct band gaps at the Γ symmetry point. According to calculated optical properties, reflectivity was low while absorption coefficients and optical conductivity were high.