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

Antimony doped tin oxide (ATO) or (SnO2: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 SnO2: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 SnO2 (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, (Sbsub), into the SnO2 lattice, causing distortion and generated oxygen vacancies. Good agreement has been found between AFM topographical images of the SnO2: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 (Eg) increases from 3.65 to 3.92 eV and then decreases. Minimum resistance sheet (Rsh) and maximum carrier concentration n achieved for SnO2:Sb thin films have been found to be 31.07 Ω cm2 and 11.8 10+19 cm−3 at 0.8 wt.% Sb doping level.