Transition Metal Doped TiO₂ Thin Films Epitaxially Grown by Reactive Sputter Deposition

Conference · Wed Jan 01 04:00:00 EST 2003

OSTI ID:1003311

Jeong, B. -S. ^[1]; Heo, Y. W. ^[1]; Budai, John D ^[2]; Park, Y. D. ^[3]; Norton, David P. ^[1]

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1. University of Florida
2. ORNL
3. Seoul National University

In recent years, there has emerged significant interest in transition-metal doped semiconducting oxide thin films, including TiO{sub 2}. Three phase of TiO{sub 2} are possible, and include rutile (tetragonal, a = 4.5845 {angstrom}, c = 2.9533 {angstrom}), anatase (tetragonal, a = 3.7842 {angstrom}, c = 9.5146 {angstrom}), and brookite (orthorhombic, a = 9.184 {angstrom}, b = 5.447 {angstrom}, c = 5.145 {angstrom}). Recently it has been reported that transition metal doped anatase can be semiconducting and ferromagnetic at room temperature. This is potentially important in the development of spin-based electronics, as this material is a potential candidate as a spin injector in spin electronic devices operating at room temperature. In this paper, we report on the epitaxial stabilization and magnetic properties of transition metal doped anatase using reactive sputter deposition. The film growth experiments were performed in a reactive RF magnetron sputter deposition system. For epitaxially stabilized anatase film growth, (001) LaAlO{sub 3} was chosen as the substrate as it provides a lattice mismatch on the order of 0.2%. X-ray diffraction pattern indicates that these films are epitaxial anatase stabilized on a (001) LaAlO{sub 3} surface. Figure 1 shows the x-ray diffraction pattern for a TiO{sub 2} film. The resistivity and carrier concentration for Co{sub 0.07}Ti{sub 0.93}O{sub 2} was 7.18{Omega}-cm and 8.09 x 10{sup 17}/cm{sup 3}, respectively. The material was n-type. For material doped with Co, ferromagnetism is observed. Figure 2 shows the magnetization vs. field curve for a Co-doped TiO{sub 2} film. This room temperature data clearly shows hysteretic behavior. In other work on Co-doped anatase, the role of Co or Ti-Co-O secondary phases has been of significant interest. Field emission SEM show that segregation of a Co-rich phase is observed in the film with high doping of Co.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1003311
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
DEPOSITION
FERROMAGNETISM
FIELD EMISSION
MAGNETIC PROPERTIES
MAGNETIZATION
MAGNETRONS
OXIDES
RUTILE
SEGREGATION
SPIN
SPUTTERING
STABILIZATION
SUBSTRATES
THIN FILMS
TRANSITION ELEMENTS
X-RAY DIFFRACTION