SYNTHESIS AND CHARACTERIZATION OF NANOCRYSTALLINE Co-DOPED ZnO THIN FILMS PREPARED BY CHEMICAL SPRAY PYROLYSIS FOR OPTOELECTRONIC APPLICATIONS

Abstract

ZnO:Co thin films were synthesized by the chemical spray pyrolysis (CSP) on glass substrates. Then, investigated the impact of Co doping concentration on its physical properties. XRD analyses show that all films have a polycrystalline structure of hexagonal ZnO. The crystallite size increased from 18[Formula: see text]nm to 25[Formula: see text]nm with Co doping concentrations. Furthermore, the unit cell volume increased from 47.485[Formula: see text]Å to 47.831[Formula: see text]Å, and the Zn–O bond length expanded from 1.97588[Formula: see text]Å to 1.98071[Formula: see text]Å. SEM observations reveal the formation of fiber-like nanostructures in the Co-doped thin films. The diameter of nanofibers increased with Co doping concentration from 260[Formula: see text]nm to 700[Formula: see text]nm. The optical characteristics were studied by the UV-Visible spectrophotometer and manifest the optical transparency vary with Co doping. In addition, the band gap decreases from 3.27[Formula: see text]eV to 2.73[Formula: see text]eV with increasing Co doping concentrations. The conductivity varied from 3.35[Formula: see text]S[Formula: see text][Formula: see text][Formula: see text]m[Formula: see text] to 19.88[Formula: see text]S[Formula: see text][Formula: see text][Formula: see text]m[Formula: see text] with Co doping concentrations. Empirical models were proposed to evaluate the correlated variables with excellent accuracy with the experimental data. The best result was accomplished in ZnO:Co1% films, where good transparency and high conductivity were achieved.