Atomic and electronic structures of a vacancy in amorphous silicon

Andreas Pedersen, Laurent Pizzagalli, Hannes Jónsson

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Locally, the atomic structure in well-annealed amorphous silicon appears similar to that of crystalline silicon. We address here the question whether a point defect, specifically a vacancy, in amorphous silicon also resembles that in the crystal. From density-functional theory calculations of a large number of nearly defect-free configurations, relaxed after an atom has been removed, we conclude that there is little similarity. The analysis is based on formation energy, relaxation energy, bond lengths, bond angles, Voronoï volume, coordination, atomic charge, and electronic gap states. All these quantities span a large and continuous range in amorphous silicon and while the removal of an atom leads to the formation of one to two bond defects and to a lowering of the local atomic density, the relaxation of the bonding network is highly effective, and the signature of the vacancy generally unlike that of a vacancy in the crystal.

Original languageEnglish
Article number054204
JournalPhysical Review B
Issue number5
Publication statusPublished - 1 Feb 2020

Bibliographical note

Funding Information:
We would like to thank G. Barkema for providing us the initial CRN model. The computations were carried out using the Nordic High Performance Computing (NHPC) facility in Iceland. We acknowledge financial support from the Icelandic Research Fund and the French foreign ministry, within the Icelandic-French project called Jules Verne. A.P. also acknowledges financial support from the Région Poitou-Charentes for his stay at the Prime Institute.

Publisher Copyright:
© 2020 American Physical Society.


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