Effect of Mn doping on the electrical and optical properties of SnO2 thin films deposited by chemical spray pyrolysis technique

• Mn:SnO2 thin films deposited with different doping concentration by spray pyrolysis technique
• Structural information confirms that all the films are polycrystalline and tetragonal crystal structure.
• XPS studies confirm the oxidation state of Mn (3 +) and Sn (4 +) in Mn:SnO2 thin film.
• 0.4 at.% of Mn:SnO2 thin film shows lowest sheet resistance 22.8 Ω/□.
• Optical band gap of 1.2 at.% Mn:SnO2 thin film is about 3.70 eV.

Manganese doped tin oxide (Mn:SnO2) thin films were deposited by spray pyrolysis technique adding various concentrations of manganese acetate (0–8 at.%) in the spray solution of tin chloride. X-ray diffraction studies show the preferred growth along (301) direction for 0.0–2.0 at.% concentration of manganese acetate in the spray solution. Higher doping concentration of manganese acetate (4 and 8 at.%) in the solution shifts the preferred growth direction along (200) plane. Scanning electron microscopic studies reveal the change in the surface morphology of the films due to various levels of Mn doping. X-ray photoelectron spectroscopic analysis shows that in the prepared thin film manganese atoms exist in Mn3 + state. The sheet resistance of SnO2 film decreases from ~ 23.5 Ω/□ to 22.8 Ω/□ for 0.4 at.% doping concentration and increases with increasing Mn concentration in the solution. The average optical transmittance of SnO2 thin film increases from 34% to 55% in the wavelength region of 550–850 nm with increase in Mn concentration. Mn concentration in the films influences the intensity of the photoluminescence emission peak observed for SnO2 film at 398 nm.