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Chromium catalysed silicon nitridation
Authors:C. G. Cofer  J. A. Lewis
Affiliation:(1) Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 61801 Urbana, Illinois, USA
Abstract:
Silicon powder compacts were fabricated with various amounts of chromium (0–5 at %) deposited onto the surface of the silicon powder by a solution-deposition process. These compacts were heated to several maximum temperatures in the range 1100–1250DaggerC in a flowing 10% H2/90% N2 atmosphere to evaluate the effect of the chromium content on the silicon nitridation. It was observed that silicon compacts containing 5 at % Cr were fully nitrided in approximately 3 h at 1150DaggerC, while less than 8% nitridation was achieved for pure-silicon compacts (with 0 at % Cr) compacts under the same conditions. Single-crystal silicon wafers with a 50 nm chromium layer were also nitrided; this provided a planar geometry, which facilitated our study of the catalysis mechanism. The rate-controlling process was shown to be first order, which may be indicative of a nucleation-and-growth mechanism, which is commonly observed for agr-silicon-nitride formation. This work demonstrates the feasibility of producing reaction-bonded silicon nitride at low temperatures using chromium catalysis, and it indicates the potential for fabricating fibre-reinforced silicon-nitride composites containing thermally sensitive fibres.
Keywords:
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