Structural, Optical and Photoluminescence Study of Nanocrystalline SnO₂ Thin Films Deposited by Spray Pyrolysis

Abstract

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 nm 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 nm is observed in photoluminescence spectra of the films along with a blue emission, when excited at 250 nm 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.