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PREPARATION AND PROPERTIES OF DIAMOND-LIKE CARBON FILMS AND INTERCALATED GRAPHITE FIBERS (PLASMA DEPOSITION)
Abstract
Experimental methods are outlined for the preparation of hard, semitransparent, 'Diamond-like' carbon films on oriented, polished crystal wafers of silicon and gallium arsenide as well as on potassium bromide flats, quartz plates and glass plates. Properties of the films are determined using infrared and visible absorption spectroscopy, ellipsometry, Auger, ESCA and conductance - capacitance spectroscopy. Preparation techniques include r.f. plasma decomposition of hydrocarbons (methane, ethylene, propane and propylene) and dual ion beam sputtering. In general, the films showed slight, or no traces of oxygen. The maximum optical bandgap obtained was 2.7 e.v. The optical absorption studies indicate a downward trend for the optical bandgap with increasing negative d.c. bias on the substrates. The annealed samples indicate a gradual narrowing of optical bandgap with increasing anneal temperatures, as well as a loss in their diamond-like quality. Infrared spectra showed the presence of hydrogen in these films. Ellipsometry studies indicated a range of refractive index of 1.8-2.2 for wavelengths in the visible region of the spectrum. The low frequency dielectric constant was found to be 3.4. In the other part of the work, highly graphitized pitch based carbon fibers were intercalated with copper chloride, antimony pentachloride, iodine chloride, nitric acid and bromine. These were reacted either singly or sequentially. The electrical resistivities were measured before and after intercalation, in air, and tests for air and thermal stability were done. A quantitative measurement of mobility was made using the Shubnikov-deHaas effect. The procedures adopted were successful in reducing the resistivity of the intercalated fibers to as low as 15.7 micro ohm-cm. For the first time negative magnetoresistance, and the Shubnikov-deHaas effect were found to be present simultaneously in intercalated fibers. The intercalated fibers exhibited a scattering time a factor of 5 smaller than typically found in Highly Oriented Pyrolytic Graphite.
Subject Area
Materials science
Recommended Citation
NATARAJAN, VENKATARAMANAN, "PREPARATION AND PROPERTIES OF DIAMOND-LIKE CARBON FILMS AND INTERCALATED GRAPHITE FIBERS (PLASMA DEPOSITION)" (1984). ETD collection for University of Nebraska-Lincoln. AAI8504812.
https://digitalcommons.unl.edu/dissertations/AAI8504812