Influence of Cu incorporation on ionic conductivity and dielectric relaxation mechanism in NiO thin films synthesized by CBD
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We present the influence of copper incorporation on ionic conductivity and dielectric relaxation mechanism of NiOthin films deposited by chemical bath deposition (CBD) method in this report. Structural and optical characterization of NiO and Cu:NiO thin films were carried out using XRD and UV–Vis spectroscopy. Increase in grain size and decrease in average microstrain in doped films were confirmed from XRD analysis. The spectrophotometric measurement shows band gap decreases with increase in dopant concentration. Impedance spectroscopy, modulus spectroscopy and dielectric study has been performed for ac electrical characterization. Impedance spectroscopy analysis confirmed enhancement of ac conductivity withCu incorporation suggesting an increase in charge carrier concentration due to doping. Enhancement in both real and imaginary part of dielectric constant was observed with Cu doping in NiO thin films. Activation energy to electrical transport process was determined from dc conductivity analysis and migration energy of charge carriers was determined from modulus spectroscopy analysis. Cole–Cole plot shows both grain and grain boundary contributes towards total resistance and capacitance. The overall resistance was found to decrease with Cu incorporation in NiO thin film. The observed results suggest hopping mechanism of charge carriers towards electrical conduction process.
One of the authors (MRD) acknowledges University Grants Commission (UGC), India for proving Junior Research Fellowship (Ref. No. 21/12/2014(ii)EU-V) during the work. The authors wish to acknowledge the University Grants Commission (UGC), India, for granting Centre for Advanced Study (CAS) under the thrust area ‘‘Condensed Matter Physics including Laser applications’’ to the Department of Physics, Burdwan University (No F. 530/5/CAS/2011(SAP-I)). The authors also acknowledge Dr. A. Datta and S. Bandyopadhyay, Dept. of Physics, The University of Burdwan for recording electrical data.
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