Exceptionally high-temperature in-air stability of transparent conductive oxide tantalum-doped tin dioxide

Abstract

The compositional, optical and structural stability of transparent conductive oxide SnO₂:Ta (1.25 at% Ta) thin films at 650 °C and 800 °C in air was studied under isothermal conditions. After the high-temperature treatment, the elemental composition and the optical spectra of the material were unchanged. X-ray diffraction confirmed the conservation of a single rutile-type phase. Two strong Raman lines located out of the SnO₂ phonon range indicated point defects in the material, which were identified as Sn vacancies and O interstitials by theoretical calculations. These point defects were partially healed out during the high-temperature treatment, without affecting the transmittance and reflectance of the material. Our study demonstrates an exceptionally high in-air stability of Ta-doped SnO₂ and encourages its application in fields, where transparent conductive oxides with high-temperature and oxidation stability are required. These are, e.g., selective transmitters for concentrated solar power or electrodes for dye-sensitized solar cells and dynamic random-access memories.