Vacancy-like defects in nanocrystalline SnO₂: influence of the annealing treatment under different atmospheres

Abstract

The study of electronic and chemical properties of semiconductor oxides is motivated by their several applications. In particular, tin oxide is widely used as a solid state gas sensor material. In this regard, the defect structure has been proposed to be crucial in determining the resulting film conductivity and then its sensitivity. Here, the characteristics of vacancy-like defects in nanocrystalline commercial high-purity tin oxide powders and the influence of the annealing treatment under different atmospheres are presented. Specifically, SnO₂ nanopowders were annealed at 330 °C under three different types of atmospheres: inert (vacuum), oxidative (oxygen) and reductive (hydrogen). The obtained experimental results are discussed in terms of the vacancy-like defects detected, shedding light to the basic conduction mechanisms, which are responsible for gas detection.

Keywords:

• Tin oxide
• nanocrystals
• point defects
• positron annihilation
• Raman spectroscopy
• electrical conductivity

Acknowledgements

M. A. P. and C. M. A. wish to thank Mr Nicolás Tibaldi for his technical assistance.