Investigation of physical, electrical and optical properties of sol-gel deposited Sc-loaded CdO films

For the first time, Sc-loaded CdO thin layers have been deposited with a sol-gel process by using Cd(CH3COO)2·2H2O and ScCl3 salts. The Sc-contribution effect on the crystalline, surface, electrical, and optical features have been inquired by means of XRD, AFM, SEM, Four Probe method, and UV/VIS spectrophotometer. The polycrystalline cubic CdO nano-particles with (111) preferential direction were observed from XRD studies. The average crystallite size, micro-strain values of Sc-loaded CdO samples changed between 22.05-17.16 nm and 2.46 × 10−3-3.16 × 10−3. The SEM and AFM images indicated that CdO samples have been composed of nano-sized spherical particles. The most homogeneous particle distribution was observed for 1 at.% Sc-contribution level and the particle sizes of pure and Sc-loaded CdO samples varied between about 30-200 nm. The sheet resistance values of films were found in the range of 5.0 × 103 Ω and 2.1 × 102 Ω. The optical transmittance and reflectance values for samples have been found between 65 and 90% and 5-22% over visible region. The optical band gap for pure CdO firstly went up from 2.63 eV to 2.66 eV with 1 at.% Sc-doping ratio and then it continuously decreased. The Urbach tail, extinction coefficient, dielectric constant and refractive index values were also determined as depending on Sc-doping content. As a result of the present research, it was seen the Sc-contribution level affected the crystallite size, lattice constant, micro-strain, optical band gap and sheet resistance values of CdO.