Structural and optical properties of phosphorous and antimony doped ZnO thin films deposited by spray pyrolysis: a comparative study



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International Advanced Research Journal in Science, Engineering and Technology


A study of structural and properties of pure (undoped) Zinc oxide (ZnO) and phosphorous (P) and Antimony(Sb) doped Zinc Oxide films has been carried out. The films were deposited by an automated spray pyrolysisequipment on both microscope glass at various elevated temperatures (270 oC - 420 oC) and on fluorine doped tinOxide (FTO) substrates at 420 oC. Structural characterization using Raman spectroscopy showed the presence of themain peak for ZnO at 437 cm-1for all the films. Antimony doped films showed other peaks associated with the dopingbut phosphorous doping did not show extra peaks. Optical characterization using a UV-VIS-NIR Shimadzu (ModelDUV 3700) double beam spectrophotometer provided both reflectance and transmittance data and Scout software wasused to compute the band gap. At a wavelength of 600 nm, the average transmittance of the pure ZnO films was ~62% while it was transmittance was ~85 % and ~80 % for Sb and P doped films respectively, an increase of ~23 % and~18 % respectively. For the undoped ZnO films, high deposition temperatures led to band gap narrowing from 3.25eVto 3.10eVwhile doping resulted in band gap widening from 3.10 eV to 3.30 eV (for P-doped) and 3.10 eV to 3.33 eV(for Sb-doped),an observation confirmed by the increased transmittance on doping. The band gap narrowing for ZnOfilms makes the film become a better materials for visible light absorption which is good for photovoltaic applications.The wide gap broadening on doping makes the film more transparent to solar radiation making it suitable fortransparent conducting oxide applications.