Structural, optical and photoluminescence study of nanocrystalline SnO2 thin films deposited by spray pyrolysis

Undoped SnO2 thin films prepared by spray pyrolysis method reveal polycrystalline nature with prominent peaks along (110), (101) and (211) planes. All the films are nanocrystalline with particle size lying in the range of 3.14-8.6 am calculated by DS formula. Orientation along plane (200) decreases continuously as molar concentration of SnO2 increases. Dislocation density along plane (110) also decreases as molar concentration increases except 0-4 M SnO2 thin film. Scanning electron microscopy image of the films contain jelly structures along with agglomerated clusters of particles. SnO2 synthesized successfully, which confirms by Fourier transform infra-red spectroscopy. The optical transmittance spectra of 0.2 M SnO2 thin film shows transmittance about 50-60% transmission in visible and near infrared region with a sharp cut off in the ultraviolet region. The transmission decreases in visible and near infrared region as molar concentration increases. Broad UV emission at 398 am is observed in photoluminescence spectra of the films along with a blue emission, when excited at 250 am wavelength. Emission intensity randomly changed as SnO2 molar concentration increases. When excited at 320 nm, one UV and two visible peaks appeared at 385, 460 and 485 nm, respectively.