Impact of zinc doping on structural, optical, and electrical properties of CdO films prepared by sol–gel screen printing mechanism

Abstract

The simple, economical, eco-friendly sol–gel screen printing mechanism is used to incorporate pure and different zinc- (2, 4, 6, 8%) doped cadmium oxide films on glass substrate at 500 °C calcination temperature. X-ray diffraction (XRD) pattern of prepared films supports the polycrystalline and cubical nature of prepared films. High intensity peak is available at (111) plane for all prepared films. The average crystallite size and strain have been calculated by Williamson–Hall method for all films. The scanning electron microscope (SEM) confirms the impact of zinc on structural morphology of cadmium oxide films. Cd, Zn, O, and absence of any kind of impurities in prepared films has been confirmed by EDAX. It also supports the decrease in atomic percentage of Cd and O with an increase in zinc doping. UV–visible spectroscopy (300–900 nm) of prepared films confirms that the transmittance of films increases up to 60% with 6% doping of zinc and with 8% doping of zinc it decreases. It is also observed that the bandgap first increases up to 2.62 eV on varying doping of zinc from 0 to 6% and then decreases with 8% doping of zinc which clearly shows that the optical properties of cadmium oxide films enhances with doping of zinc. Photoluminescence spectrum of films confirms that there is an enhancement in luminescence property with zinc doping. Fourier transform infrared spectroscopy (FTIR) confirms the presence of Cd–O and O–C–O vibrations in films. Two-probe method has been used for the study of electrical properties of prepared films and it is seen that the electrical resistivity decreases with increase in doping of zinc up to 6% and with 8% doping of zinc it increases.