Session H28: Focus Session: Dopants and Defects in Semiconductors - Si
8:00 AM–11:00 AM, Tuesday, February 28, 2012
Room: 258C
Sponsoring Unit:
DMP
Chair: Michael Aziz, Harvard University
Abstract ID: BAPS.2012.MAR.H28.3
Abstract: H28.00003 : Doping in Si/SiO$_{2}$ Structures: A first-principles metadynamics study
8:48 AM–9:00 AM
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Abstract 
Authors:
Nicholas Lanzillo
(Rensselaer Polytechnic Institute)
Philip Shemella
(IBM Research - Zurich)
Saroj Nayak
(Rensselaer Polytechnic Institute)
Wanda Andreoni
(IBM Research - Zurich)
Alessandro Curioni
(IBM Research - Zurich)
Dopant diffusion in semiconductor devices is a field of study with tremendous technological importance. We have performed first-principles metadynamics simulations of the diffusion of n-type dopants at the Si/SiO$_{2}$ interface using the ab-initio MD method. After the generation of a vacancy in the Si region, arsenic, phosphorus and silicon atoms show varying mechanisms of diffusion, including both substitutional and interstitial. Although at the near-interface silicon region arsenic is the first to diffuse interstitially, its interstitial position is more stable and thus less likely to diffuse across the interface relative to phosphorus and silicon. As arsenic crosses the interface, however, its relative stability decreases with respect to phosphorus and silicon and diffusion into the oxide becomes unfavorable. This is in agreement with experimentally observed arsenic pile-up at the Si/SiO$_{2}$ interface. We quantify the diffusion mechanisms by comparing free energy barriers in the silicon region as well as at the interface. We find the largest barriers exist for silicon, while the smallest barriers exist for arsenic.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2012.MAR.H28.3