Properties of Electrosynthesized Cobalt Doped Zinc Selenide Thin Films Deposited at Varying Time

Abstract

Time optimized cobalt-doped zinc selenide thin films have been successfully electrodeposited on fluorine-doped tin oxide substrates. The films were deposited at the varying time of 1 min, 3 mins, and 5 mins respectively. Film thickness, optical, structural, electrical, and morphological properties of the deposited thin films were evaluated. Film thickness estimated using the gravimetric method increased from 294.35 nm to 399.62 nm as deposition time increased. Optical properties showed that the absorbance of the films ranged from 13.58% to 83.15% and was found to increase as deposition time increased. Transmittance ranged from 24.40% to 73.15% and was found to decrease as deposition time increased. The reflectance of the films was found to be low while the energy band gap ranged between 2.10 eV and 2.85 eV. Structural properties confirmed the deposition of ZnSe thin film with crystallite size values that fall between 14.68 nm and 18.60 nm. Dislocation density is ranged from 4.66 × 10¹⁵ lines/m² to 2.97 × 10¹⁵ lines/m² while microstrain ranged between 8.53 × 10^-3 and 5.83 × 10^-3. Crystallite sizes of the films were found to increase as deposition time increased while dislocation density and microstrain were found to decrease as deposition time increased. Electrical properties showed that the deposited films are semiconducting films with electrical resistivity values of 1.54 × 10⁵ Ω cm-1.83 × 10⁴ Ω cm and electrical conductivity values of 6.30 × 10^-6 S/cm-5.47 × 10^-5 S/cm. The micrograph of the films showed that the films were made up of nanoparticles and nanofibres of different dimensions. Energy-Dispersive X-Ray Spectroscopy (EDS) spectra of the films confirmed the presence of cobalt, zinc, and selenium.