Structural Characterization of Amorphous Silicon Nitride by Molecular Dynamics Simulation(Materials, Metallugy & Weldability)

概要

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Computer simulation using the molecular dynamics (MD) technique have been carried out on amorphous silicon nitride (a-Si_3N_4) with simple Busing-type potentials. From the MD simulation, the following points have been deduced: (1) The average Si-N bond length obtained from our MD results is r_<si-N>=1.74Å, and its coordination number N_<Si/N> is 3.95. The bond angle around a Si and a N atom, *N-Si-N and*Si-N-Si, are found to be 109. 8°±12.36°and 127.08°±16.63°, respectively. The obtained*N-Si-N value is in a very good agreement with that of a tetrahedral bond angle (=109.47°). Therefore, the short-range structural arrangement of a-Si_3N_4 is composed of the tetrahedral bond angle (=109.47°). Therefore, the short-range structural arrangement of a-Si_3N_4 is composed of the tetrahedral SiN_4 units. Our MD results also indicate that there exist only a small number of defects such as dangling bonds. (2) Our MD results are in good agreement with the reported X-ray and neutron data. The a-Si_3N_4 structure can be reproduced by our MD simulation.
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