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

• Published in: Thin solid films 2005-07, Vol.484 (1-2), p.132-139
• Main Authors: BATZILL, Matthias, BURST, James M, DIEBOLD, Ulrike
• Format: Article
• Language: English
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Molecular, atomic, ion, and chemical beam epitaxy; Physics; Theory and models of film growth
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2005.02.016

Pure and Co--doped epitaxial SnO2 films grown by oxygen plasma assisted molecular beam epitaxy on r--cut alpha--alumina substrates were investigated by electron diffraction, X--ray photoelectron spectroscopy (XPS), and X--ray photoelectron diffraction (XPD). On hot alumina substrates (~800 deg 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 deg 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. CoxSn1--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.