Microstructural and Optical Characteristics of 4 at.% Sn-Doped ZnO Thin Films Deposited by Spray Pyrolysis

In the present work, 4 at.% Sn-doped ZnO (SZO) thin films were successfully deposited on glass substrates by the spray pyrolysis technique. The thin films were characterized through X-ray diffraction (XRD), UV–Visible spectroscopy, and field-emission scanning electron microscopy (FESEM). It is found through XRD studies that the thin films are polycrystalline having hexagonal wurtzite crystal structure. No additional phases corresponding to tin oxides or any other impurities were observed in XRD results suggesting incorporation of tin ions into the ZnO matrix with good phase purity. Strong optical absorption in the ultraviolet range with well-defined absorption edge confirms the existence of crystalline semiconductor material. Optical bandgap of the 4 at.% Sn doped ZnO thin film was calculated as 3.32 eV from UV–visible spectra. The FESEM images of the thin films showed dense, compact, and homogeneously distributed nanograins with complete coverage of the substrate surface and good structural integrity. The grains showed almost spherical to polygonal shape without any cracks, pinholes or voids. Structural, optical and morphological analyses suggest that 4 at.% Sn doped ZnO thin films fabricated through spray pyrolysis have desired properties for optoelectronic and sensing applications.