Influence of nickel incorporation on structural, optical and electrical characteristics of SILAR synthesized CuO thin films

• Published in: Journal of sol-gel science and technology 2018-07, Vol.87 (1), p.59-73
• Main Authors: Das, Mahima Ranjan, Mitra, Partha
• Format: Article
• Language: English
• Subjects: Capacitance; Carrier density; Ceramics; Charge density; Chemical synthesis; Chemistry and Materials Science; Composites; Copper oxides; Current carriers; Dielectric relaxation; Doped films; Doping; Electrical conduction; Electrical resistivity; Energy gap; Glass; Grain boundaries; Grain size; Impedance spectroscopy; Incorporation; Inorganic Chemistry; Materials Science; Migration; Nanotechnology; Natural Materials; Nickel; Nyquist plots; Optical and Electronic Materials; Original Paper: Functional coatings; Permittivity; Reduction; Relaxation time; Spectrophotometry; Spectrum analysis; Thin films; thin films and membranes (including deposition techniques); X-ray diffraction
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-018-4711-1

In this report, we have primarily studied the influence of nickel (Ni) incorporation on ac electrical conductivity, dielectric relaxation mechanism and impedance spectroscopy characteristics of copper oxide (CuO) thin films synthesized by successive ion layer adsorption and reaction (SILAR) technique. The materials has been characterized using X-ray diffraction and UV–VIS spectrophotometric measurements. Reduction in grain size in doped films up to a certain extent of doping (tentatively 6%) were confirmed from XRD analysis, beyond which there is a reverse tendency. Increase in band gap in doped films were observed up to 6% doping level which could be associated with enhanced carrier density in doped films. Impedance spectroscopy analysis confirmed enhancement of ac conductivity and dielectric constant for doped samples. The results are useful for capacitive application of the films. Beyond 6% doping level, AC conductivity and dielectric constant shows a reverse tendency indicating reduced density of charge carriers. Nyquist plot shows contribution of both grain and grain boundary towards total resistance and capacitance. Imaginary part of complex modulus and imaginary part of complex impedance was used to find the migration/activation energy to electrical conduction process. Nearly identical result was obtained from relaxation frequency/relaxation time approach suggesting hopping mechanism of charge carriers. Highlights Successful incorporation of Ni in CuO thin film through SILAR technique. Reduction of grain size and enhancement of band gap up to 6% Ni incorporation. Enhancement of ac conductivity and dielectric constant up to 6% Ni incorporation. Reverse tends in structural, optical and electrical characteristics beyond a certain doping level. Contribution of both grain and grain boundary towards total resistance and capacitance.