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Silicon Carbide Amorphization by Electron Irradiation

Published online by Cambridge University Press:  02 July 2020

J. Bentley
J. Bentley*
Affiliation:
Metals & Ceramics Div., Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN37831-6376
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Observations made more than ten years ago1 showed that SiC could be made amorphous at cryogenic temperatures by in-situ 300kV electron irradiation. However, high-voltage electron microscope (HVEM) results indicate a threshold voltage of 725 kV for amorphization of SiC at 140 K. In addition, a recent review exposes the considerable uncertainty in the literature regarding displacement energies for SiC. Therefore, further experiments have been performed in a Philips CM30 (LaB6 cathode) with a Gatan double-tilt cooling holder in an attempt to determine the threshold voltage for amorphization at ∼ 140 K. Sintered α-SiC (defected 6H polytype), beam direction B=< 1120 >, and probes containing ∽ 75 nA in ∽0.5 μm, were used. Amorphization occurred in <10 min at 300 kV and after ∽60 min at 180 kV (Fig. 1); visible darkening occurred at lower voltages and doses. Similar behavior occurred for B=[0001]. The critical dose for amorphization was measured as a function of accelerating voltage.

Type
Nanophase and Amorphous Materials
Information
Microscopy and Microanalysis , Volume 4 , Issue S2: Proceedings: Microscopy & Microanalysis '98, Microscopy Society of America 56th Annual Meeting, Microbeam Analysis Society 32nd Annual Meeting, Atlanta, Georgia July 12-16, 1998 , July 1998 , pp. 698 - 699
Copyright
Copyright © Microscopy Society of America

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References

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9. Research at the Oak Ridge National Laboratory (ORNL) SHaRE User Facility sponsored by the Division of Materials Sciences, U.S. Department of Energy, under contract DE-AC05-96OR22464 with Lockheed Martin Energy Research Corp. Thanks to Dr. Ian Anderson for eqn. 1, and to Drs. Ed Kenik, Steve Zinkle, and Lance Snead (ORNL), and to Dr. Linn Hobbs (MIT) for useful discussions.Google Scholar