Growth of Cr-doped TiO2 films in the rutile and anatase structures by oxygen plasma assisted molecular beam epitaxy

• Published in: Thin solid films 2005-07, Vol.484 (1-2), p.289-298
• Main Authors: OSTERWALDER, J, DROUBAY, T, KASPAR, T, WILLIAMS, J, WANG, C. M, CHAMBERS, S. A
• Format: Article
• Language: English
• Subjects: AMPLITUDES; ANISOTROPY; ATOMS; CHROMIUM; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Defects and impurities: doping, implantation, distribution, concentration, etc; DIFFRACTION; diluted magnetic semiconductor; Environmental Molecular Sciences Laboratory; epitaxial films; Exact sciences and technology; FERROMAGNETIC MATERIALS; MAGNETIZATION; MATERIALS SCIENCE; Methods of deposition of films and coatings; film growth and epitaxy; MODULATION; MOLECULAR BEAM EPITAXY; Molecular, atomic, ion, and chemical beam epitaxy; OXYGEN; Physics; PLASMA; RUTILE; SATURATION; SPECTRA; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; titanium dioxide; VALENCE
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2005.02.028

As part of a search for new spintronic materials, highly ordered films of CrxTi1--xO2 in both the rutile and anatase structures and for several Cr concentrations ranging from x=0*02 to 0*16 were grown by oxygen plasma assisted molecular beam epitaxy. X--ray photoelectron diffraction data of the Cr 2p level exhibit the same patterns and the same modulation amplitudes as those observed for Ti 2p, providing a strong indication that a large fraction of the Cr atoms occupy substitutional lattice sites in both structures. The Cr 2p core--level spectra as well as a Cr 3d related dopant signal above the valence band of TiO2 are characteristic of Cr(3)(+)ions. At room temperature, Cr--doped anatase films exhibit ferromagnetic order with a saturation magnetization of ~0*6 muB per Cr atom and strong in--plane anisotropy.