Electrical, optical and structural properties of SnO₂:Sb:F thin films deposited from Sn(acac)₂ by spray pyrolysis

In this work, Fluorine + Antimony doped Tin oxide thin films (SnO2:Sb + F), were deposited on heated glass substrates using the ultrasonic spray pyrolysis technique. Tin(IV)-bis(acetylacetonate) dichloride ((C5H8O2)2SnCl2), was used as source of Tin. The use of the latter reagent was considered important, since its usage had scarcely been reported. Antimony chloride (SbCl3) and Ammonium fluoride (NH4F) were used as sources of the dopants of Antimony and Fluorine, respectively. The properties of the films resulted dependent on the relative amount of these dopants. The films as deposited were polycrystalline, with a low roughness, and showed excellent optical transparency, close to 90%, in the visible region of the electromagnetic spectrum. Fluorine in the films was only detected by Secondary Ion Mass Spectroscopy (SIMS) measurements, and films deposited with 5% of NH4F and 5% of SbCl3 in solution, showed the best electrical properties. An electronic conductivity up to 400 S/cm, and mobility, close to 10 cm2/V sec, were found in the best SnO2 film. An ionized impurity scattering mechanism seems to be responsible for the electronic transport in these films. In addition, the electronic conduction by bulk (or grains), was verified by impedance spectroscopy.