Pure and cobalt-doped SnO₂(101) films grown by molecular beam epitaxy on Al₂O₃

M. Batzill, J. M. Burst, U. Diebold

Thin Solid Films 484 (2005) 132-139

Pure and Co-doped epitaxial SnO₂ films grown by oxygen plasma assisted molecular beam epitaxy on r-cut α-alumina substrates were investigated by electron diffraction, X-ray photoelectron spectroscopy (XPS), and X-ray photoelectron diffraction (XPD). On hot alumina substrates (∼ 800 °C) only a submonolayer amount of Sn adsorbs, indicating a strong adhesion of the first monolayer of tin on the alumina surface. SnO₂ films grown at ∼400-600 °C substrate temperature exhibit a SnO₂(101)[010]||Al₂O₃(-1012)[12-10] epitaxial relationship. Subtle differences in the XPD data of SnO₂ films compared to measurements on SnO₂(101) single crystal surfaces are consistent with the presence of a high density of stoichiometric antiphase domain boundaries in the film. These planar defects are introduced in the SnO₂ film to compensate for the more than 10% lattice mismatch between the SnO2 films and the alumina substrate along the SnO2[-101] direction. Co_xSn_1-xO₂ films with a Co-cation concentration of 5-15% were also grown. XPS indicates that Co is in a 2+ oxidation state and XPD shows that tin is replaced substitutionally by Co.

Corresponding author: U. Diebold (diebold).

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