Electrical and optical properties of iron-doped CdO

Thin films of Fe-doped CdO with 1.3, 2.0, 2.3, 3.0, and 5.7 wt.% were prepared by a vacuum evaporation method on glass and Si wafer substrates. The prepared films were characterised by X-ray fluorescence and diffraction. Results show that doping of CdO with Fe enhances the film's [111] preferred orientation and causes slight shifts in the (111) Bragg angle towards higher values. The samples were investigated with a UV–VIS–NIR absorption spectroscopy and dc-electrical measurements. It was observed that there is a complicated dependence of bandgap on the Fe wt.% content in the film. In addition, light doping with Fe improves the dc-conduction parameters of CdO, so that with 1.3 wt.% Fe doping, the mobility increases by about 6 times, conductivity by 24 times, and carrier concentration by about 4 times, relative to undoped CdO film. The observations were analysed by using the available models (with a slight modification) for the coexistence of bandgap widening and bandgap narrowing.