AVS 46th International Symposium
    Thin Films Division Monday Sessions
       Session TF-MoP

Paper TF-MoP5
Characterization of VO@sub 2@ Epitaxial Films with Different Orientations Grown on Sapphire (110) by Sputtering

Monday, October 25, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: P. Jin, National Industrial Research Institute of Nagoya, Japan
Authors: P. Jin, National Industrial Research Institute of Nagoya, Japan
S. Tanemura, National Industrial Research Institute of Nagoya, Japan
K. Macak, Linkoping University, Sweden
U. Helmersson, Linkoping University, Sweden
Correspondent: Click to Email
Vanadium dioxide is one of the most important compounds in the V-O system. It exhibits a semiconductor-to-metal phase transition at 68°C, accompanied by large changes in electrical resistivity (up to 10@super 5@) and optical properties (from transmitting to reflecting in the infrared). Thin films of vanadium dioxide have been studied for electrical and optical switching devices. It is known that an epitaxial film, which can be grown on sapphire substrate, exhibits properties comparable to single crystal. However, there is little information on the deliberate control of orientation of an epitaxial film and the effect on film property. In this study, thin films vanadium dioxide were grown using DC reactive magnetron sputtering on single crystal 110-oriented sapphire substrates held at 400-600°C. The magnetron source was of the unbalanced type giving rise to more intense bombardment as compared to conventional sources. Different film orientations was achieved with different sputtering geometry, most likely due to varying energetic particle bombardment and growth rate, i.e., an on-axis deposition (substrate facing target) and an off-axis deposition resulted in well-defined (100)- and (001)- oriented epitaxial films, respectively. The epitaxial films were examined by x-ray diffraction using conventional @theta@-2@theta@ scans, rocking curves, and pole figure plots. The compositions were determined from Rutherford backscattering spectroscopy (RBS) and the surface morphologies were studied with atomic force microscopy (AFM). The different film orientations resulted in significant difference in film properties such as the temperature and sharpness of the phase transition, as confirmed from the measurement of electrical resistance vs temperature.