Atmospheric plasma discharge chemical vapor deposition of SnOx thin films using various tin precursors

Abstract A series of 0.2–0.6 μm thick SnO x films were deposited onto borosilicate and sodalime silica glass substrates by atmospheric plasma discharge chemical vapor deposition at 80 °C. SnO x films deposited from monobutyltin trichloride contained a large percentage of SnCl 2 :2H 2 O, and therefore were partially soluble in water. SnO x coatings deposited from tetrabutyltin were not soluble in water or organic solvents, had good adhesion even at growth rates as high as 2.3 nm/s, had high transparency of ∼ 90% and electrical resistivity of 10 7 Ω cm. As-grown tin oxide coatings were amorphous with a small concentration of SnO 2 , SnO and Sn crystalline phases as determined by grazing angle X-ray diffraction and X-ray photoelectron spectroscopy measurements. Upon annealing in air at 600 °C the resistivity of SnO x films decreased to 5–7 Ω cm. Furthermore, optical and X-ray measurements indicated that SnO x was converted into SnO 2 (cassiterite) with a direct band gap of 3.66 eV. Annealing of as-grown SnO x films in vacuum at 340 °C led to formation of the p-type conductor SnO/SnO x . The indirect band gap of SnO was calculated from the optical spectra to be 0.3 eV.