Influence of Mn incorporation on ionic conductivity and dielectric relaxation process in CBD synthesized CdO thin films

We present the influence of manganese incorporation on ionic conductivity and dielectric relaxation mechanism of CdO thin films synthesized by chemical bath deposition (CBD) method. Structural, optical and ac electrical characterization of CdO and Mn:CdO thin films has been carried. The materials were characterized using X-ray diffraction and UV-VIS spectrophotometer. Increase in grain size and decrease in average microstrain in doped films were confirmed from XRD analysis. Decrease in band gap in doped films were observed from spectrophotometric measurements. Impedance spectroscopy analysis confirmed enhancement of ac conductivity with Mn incorporation suggesting an enhancement in charge carrier concentration due to doping. Enhancement in both real and imaginary part of dielectric constant was observed with Mn doping. Cole-Cole plot shows contribution of both grain and grain boundary towards total resistance and capacitance. The overall resistance was found to decrease with Mn incorporation in CdO film. Activation energy to electrical transport process was determined from dc conductivity analysis and migration energy of charge carriers was determined from modulus spectroscopy analysis. The observed results suggest hopping mechanism of charge carriers towards electrical conduction process.