Microstructure and physical properties of sol gel derived SnO2:Sb thin films for optoelectronic applications

Abstract

Antimony doped tin oxide thin films were deposited on glass substrates by sol-gel dip coating technique. X-ray diffraction pattern showed the deterioration of the crystallinity of the films with increase in antimony doping concentration. Atomic force microscopy studies showed an inhibition of grain growth with increase in Sb concentration.The rms roughness value of SnO2:Sb thin films are found to 1% of film thickness which makes them suitable for optoelectronic applications. The film surface revealed positive skewness and high kurtosis values which make them favorable for tribological applications. The lowest resistivity (about10−5Ωm) was obtained for the 5mol% Sb doped SnO2: Sb films. These films acquire n-type conductivity due to non- stoichiometry (oxygen vacancies and interstitial tin atoms) and by the addition of Sb. The optical properties of the films have been studied from transmission spectra. An average transmittance of >80% (in UV–vis region) was observed for all the films. Optical band gap energy of SnO2:Sb films were found to vary in the range of 3.69–3.97eV with the increase in Sb doping concentration. Photoluminescence spectra of the films exhibited an increase in the emission intensity with increase in antimony doping concentration which is due the combined effect of charge balance and decrease in grain size. The enhancement of PL intensity in the antimony doped SnO2 thin films make it suitable for generation of solid state lighting in light emitting diode.