Polycrystalline Sn-doped films were prepared by means of reactive radio-frequency diode sputtering, of an oxidic target, using various O/Ar mixtures. The specimens usually contained more O than an ideal crystal. When deposited at low pressures, the crystals had an expanded (by up to 3.5%) lattice. For small O additions to the sputtering gas, they were also denser than an ideal crystal. This was attributed to the incorporation of additional O into the bixbyite structure, and perhaps into constitutional vacancies. During annealing, the lattice relaxed and additional O remained in the films. A model for O segregation into grain boundaries was developed which could also explain the grain/sub-grain structures which had been reported for such films.

Oxygen Incorporation into Thin Films of In2O3:Sn Prepared by Radio-Frequency Sputtering. D.Mergel, W.Stass, G.Ehl, D.Barthel: Journal of Applied Physics, 2000, 88[5], 2437-42