Electrical properties of bulk and interface layers in Sb doped SnO2 thin films

Sb doped SnO2 (ATO) thin films with various thicknesses have been prepared by magnetron sputtering on glass substrates and investigated for the electrical properties (resistivity, carrier concentration and mobility) of bulk and interface layers in the thin films. The thin films are polycrystalline with the cassiterite tetragonal (rutile type) structure. According to the AFM measurement, it can be found that the average surface grain sizes are almost the same for the thin films with various thicknesses. The valence state of the Sb donors in the film is determined by X-ray photoelectron spectroscopy, the results confirm that the Sb donors are effectively in the oxidation state Sb5+ in the ATO thin films. Based on the parallel resistance model, the resistivity of 2.12 x 10(-3) Omega cm, carrier concentration of 1.88 x 10(20) cm(-3) and mobility of 15.68 cm(2) V-1 s(-1) for the bulk layers are obtained through the measurement of the Hall effect. The thickness (14.1 nm) of interface layers is achieved via the measurements of the optical refractive characteristics. Combining the data, the resistivity, carrier concentration and mobility of interface layers are respectively calculated to be 2.82 x 10(-1) Omega cm, 1.13 x 10(19) cm(-3) and 1.96 cm(2) V-1 s(-1).