Optical and electronic properties of high quality Sb-doped SnO2 thin films grown by mist chemical vapor deposition

Abstract

Transparent Sb-doped epitaxial SnO2 (101) thin films were grown via mist chemical vapor deposition, a nonvacuum solution-based technique that involves the gas-assisted transport of ultrasonically-generated aerosols from simple aqueous Sn and Sb precursors. The electrical properties (at 300 K) of the resulting films could be varied from insulating to semimetallic via Sb doping, with a minimum resistivity of 8×10−4Ωcm, carrier concentrations up to 3.93×1020cm−3, and a maximum mobility of 48.1±0.1cm2V−1s−1, results similar to those achieved using molecular beam epitaxy and other more-sophisticated high vacuum techniques. Secondary ion mass spectrometry and Hall effect measurements revealed that 14% of Sb in the precursor solution incorporates into the Sb:SnO2 films, with almost all the Sb atoms forming shallow substitutional donors on the Sn-site. The increase in the carrier concentration with Sb doping produced a Burstein-Moss shift of the optical gap of 0.49 eV, without significantly reducing the more than 90% transparency of the films in the visible region. X-ray photoemission spectroscopy (hν=1486.6eV) showed an asymmetric Sn3d5/2 core-level emission characterized by a carrier concentration-dependent peak splitting. This effect was modeled in terms of the creation of an intrinsic plasmon loss satellite from which a conductivity effective electron mass of (0.49±0.11)me was determined.