Insights into the consequence of (Al–Zn) dual-doping on structural, morphological, and optoelectrical properties of CdO thin films

Abstract

The present study explores the structural, morphological, optical, and electrical properties of spray pyrolyzed (Al–Zn) dual-doped CdO thin films. The un-doped and (Al–Zn) dual-doped CdO thin films have been deposited on glass substrate using spray pyrolysis route at 325 °C. The physical properties of the doped samples were analyzed as a function of Zn concentration (2–5 mol%) with constant Al (3 mol%) concentration. XRD analysis confirms the successful incorporation of (Al–Zn) dual-doping into CdO crystal as well as the polycrystalline nature was evident. No phase transitions were apparent from XRD data while revealing the single cubic structure of all the samples. The surface morphology of the samples studied by SEM. It shows the formation of rock-shaped microstructure and the variation of grain size with doping concentrations. Optical analysis was done using UV–vis spectroscopy within the range of 300–1200 nm. Maximum value of transmittance was attained for 3% (Zn–Al)-doped CdO sample. The dual doping exhibits the broadening of band gap values (2.61–3.84 eV) whereas a decrease in extinction coefficient was noticed as a function of Zn doping concentration. Electrical analysis was done using the four-probe method and a high resistivity was seen for higher Zn concentration. Obtained results and precise comparison with some similar films suggested that 2% Zn and 3% Al co-doping can be a suitable candidate for optoelectronic devices.

Keywords

• Cadmium oxide thin film
• Zinc- Aluminium dual-doping
• Spray pyrolysis
• Structural properties
• Optoelectrical properties