AVS 45th International Symposium
    Thin Films Division Monday Sessions
       Session TF-MoP

Paper TF-MoP9
Growth and Characterization of Epitaxial Films of Tungsten-Doped Vanadium Oxides on Sapphire (110) by Reactive Magnetron Sputtering

Monday, November 2, 1998, 5:30 pm, Room Hall A

Session: Thin Films Poster Session
Presenter: P. Jin, National Industrial Research Institute of Nagoya, Japan
Authors: P. Jin, National Industrial Research Institute of Nagoya, Japan
M. Tazawa, National Industrial Research Institute of Nagoya, Japan
M. Ikeyama, National Industrial Research Institute of Nagoya, Japan
S. Tanemura, National Industrial Research Institute of Nagoya, Japan
K. Macak, Linkoping University, Sweden
X. Wang, Linkoping University, Sweden
U. Helmersson, Linkoping University, Sweden
Correspondent: Click to Email
Some vanadium oxides undergo a semiconductor-to-metal phase transition with significant changes in optical, electrical and magnetic properties. Replacement of V by metals such as W, Mo affects greatly the properties. Since thin films of such materials are candidates for switching or memory devices, it is necessary to investigate the growth, structure and properties of the metal-doped vanadium oxides particularly in the form of epitaxial film. In this study, films of W-doped vanadium oxides were epitaxially grown on sapphire (110) by reactive sputtering a V-W alloy target. With computer control of deposition parameters, especially the oxygen flow into the Ar+O@sub 2@ discharge, a series of epitaxial films having structures of not only the best known MO@sub 2@ (M=V+W) but also others from M@sub 2@O@sub 3@ to M@sub 2@O@sub 5@ were obtained. The films were studied with X-ray diffraction (XRD), atomic force microscopy (AFM), Rutherford backscattering spectrometry (RBS), etc. The XRD theta-2theta scan shows only pairs of peaks corresponding to those from the film and the substrate. Furthermore, a series of films formed by varying slightly the oxygen flow exhibit a continuous shift of the XRD peaks in response to their metal-to-oxygen ratio. In other words, a continuous structural change was obtained by precise process controlling. The XRD pole figure study confirmed the epitaxial relationships. The phase transition properties were studied from the change in electrical resistivity against temperature. The results demonstrate strong influences both from the metal-to-oxygen ratio and the tungsten doping amount.