Volume 79, Number 3, August 2007
|Number of page(s)||5|
|Section||Condensed Matter: Structural, Mechanical and Thermal Properties|
|Published online||13 July 2007|
Thermally stimulated H emission and diffusion in hydrogenated amorphous silicon
Department of Physics and Astronomy, Ohio University - Athens, OH 45701, USA
Accepted: 15 June 2007
We report first principles ab initio density functional calculations of hydrogen dynamics in hydrogenated amorphous silicon. Thermal motion of the host Si atoms drives H diffusion, as we demonstrate by direct simulation and explain with simple models. Si-Si bond centers and Si ring centers are local energy minima as expected. We also describe a new mechanism for breaking Si-H bonds to release free atomic H into the network: fluctuating bond center detachment (FBCD)-assisted diffusion, in which a bond center H may be liberated by intercession of a third nearby Si. H dynamics in a-Si:H is dominated by structural fluctuations intrinsic to the amorphous phase not present in the crystal.
PACS: 66.30.Jt – Diffusion of impurities / 66.30.-h – Diffusion in solids / 61.43.Dq – Amorphous semiconductors, metals, and alloys
© Europhysics Letters Association, 2007
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