Doping concentration and annealing temperature effects on the properties of nanostructured ternary CdZnO thin films towards optoelectronic applications

Nanostructured ternary CdZnO thin films with zinc concentrations (0, 2, 4, 6 and 8 wt%) were prepared by spray pyrolysis technique using perfume atomizer on glass substrates at 375 °C. The effect of doping concentration on the structural, morphological, optical and electrical properties of the films was studied and from the results obtained it is observed that the CdZnO film with 6 wt% Zn doping concentration has better physical properties and this film is subjected to post annealing in air at different temperatures. The effect of thermal annealing on the properties of the deposited films was systematically studied. The XRD patterns reveal that the films are polycrystalline in nature with cubic structure and are highly textured along (1 1 1) preferential orientation. The SEM and AFM images confirmed these results and showed more crystallization up to 300 °C annealing temperature. Film transparency decreases with annealing temperature. Analysis of the absorption edge revealed that the optical band gap energies of the films was red shifted with annealing temperature. The annealed films have a resistivity in the order of 101 Ω cm. Increased transparency and reduced resistivity observed for the CdZnO films make them suitable for optoelectronic device applications especially as window layer in solar cells.

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