AVS 47th International Symposium
    Thin Films Tuesday Sessions
       Session TF-TuP

Paper TF-TuP34
Structural Characterization of Tungsten Trioxide Thin Films

Tuesday, October 3, 2000, 5:30 pm, Room Exhibit Hall C & D

Session: Poster Session
Presenter: L.J. LeGore, University of Maine
Authors: L.J. LeGore, University of Maine
R.J. Lad, University of Maine
J.F. Vetelino, University of Maine
B.G. Frederick, University of Maine
E.A. Kenik, Oak Ridge National Laboratory
Correspondent: Click to Email
Tungsten trioxide is a wide band-gap n-type semiconductor which has been used as a sensing material in conductance-type gas sensors. The microstructure and morphology is believed to have a large influence on the sensitivity, selectivity, and stability of the sensor. We have produced tungsten trioxide thin films 15 nm to 600 nm thick by reactive rf magnetron sputtering onto r-cut sapphire substrates. The microstructure of the films was characterized by reflection high energy electron diffraction (RHEED), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). By controlling the substrate deposition temperature and by post-deposition annealing, films from highly oriented epitaxial to random polycrystalline were produced. All films were found to be dense with low porosity. The epitaxial films were nearly atomically smooth while the polycrystalline films were significantly rougher. Lattice parameter measurements at room temperature indicate the possibility of more than one crystallographic phase.