Effect of Zn doping on structural, morphological, optical and electrical properties of nebulized spray-deposited CdO thin films

Transparent and conducting pure and Zn-doped CdO thin films (0, 1, 2, 3 and 4 at.% Zn) have been successfully deposited on glass substrates at optimized substrate temperature of 200 degrees C by spray pyrolysis technique using nebulizer. Structural, morphological, optical and electrical properties of pure and Zn-doped CdO thin films are studied in detail. X-ray diffraction study confirms that all the CdO thin films were polycrystalline in nature with major reflection alone (111) plane having a cubic structure. The high average grain size (345 nm-SEM) and low RMS (6.46 nm-AFM) values are obtained for 3 at.% Zn-doped CdO thin films. The optical band gap energy had increased from 2.49 to 2.57 eV as the function of doping concentration had increased from 1 to 3 at.% Zn and thereafter decreased for higher doping concentration. A strong green emission and slightly shifted for Zn-doping concentration of CdO thin films exhibited by photoluminescence spectra. The CdO bond vibration confirmed by FTIR and Raman analyzes. The resistivity value of un-doped CdO thin film is 1.06 x 10(-3) Omega cm and adding Zn-doped concentration, the resistivity consequently decreased to 6.2 x 10(-4) Omega cm for 3 at.% Zn-doped CdO thin films and then furthermore increased. A high-quality factor (7.07 x 10(-2)) was obtained for 3 at.% Zn-doped CdO thin films.