Effect of fluorine doping on the structural, optical and electrical properties of SnO2 thin films prepared by spray ultrasonic

Abstract Antimony doped tin oxide (ATO) or (SnO 2 :Sb) thin films have been prepared by spray ultrasonic on heated glass substrates at 480 °C for 3 min as time deposition. The dependence of structural, optical and electrical properties of SnO 2 :Sb films on the Sb concentration (0–1 wt.%), is investigated. X-ray diffraction pattern reveals the presence of cassiterite structure with (2 1 1) as preferred orientation for ATO films with presence of other orientations. Focused analysis, on (2 1 1) peaks, indicated that the interplanar spacing of SnO 2 (2 1 1) increases, after Sb doping until 0.8 wt.% level, due to the substitution of some Sn +4 by some Sb in Sb +3 state, (Sb sub ), into the SnO 2 lattice, causing distortion and generated oxygen vacancies. Good agreement has been found between AFM topographical images of the SnO 2 :Sb samples and XRD grain size measurements. The crystallite size varies from 24.93 to 33.25 nm and was affected by Sb concentration whereas the lattice parameters ( a and c ) are found to increase with Sb doping concentration until 0.8 wt.% level and then decrease. Transparency in the visible range was around ∼80%. At Sb doping level lower than 0.8 wt.%, all the envelope of transmission T ( λ ) curves become contracted and shift toward lower wavelength revealing the effect of plasma carrier concentration in absorbing light. The optical band gap ( E g ) increases from 3.65 to 3.92 eV and then decreases. Minimum resistance sheet ( R sh ) and maximum carrier concentration n achieved for SnO 2 :Sb thin films have been found to be 31.07 Ω cm 2 and 11.8 10 +19  cm −3 at 0.8 wt.% Sb doping level.