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Title: A mechanistic study of impurity segregation at silicon grain boundaries

The segregation behavior of carbon and oxygen atoms at various silicon grain boundaries was studied using a combination of atomistic simulation and analytical modeling. First, quasi-lattice Grand Canonical Monte Carlo simulations were used to compute segregation isotherms as a function of grain boundary type, impurity atom loading level, and temperature. Next, the atomistic results were employed to regress different analytical segregation models and extract thermodynamic and structural properties. The multilayer Brunauer–Emmett–Teller (BET) isotherm was found to quantitatively capture all the simulation conditions probed in this work, while simpler, single layer models such as the Langmuir-McLean model did not. Some of the BET parameters, namely, the binding free energy of the first adsorption layer and the impurity holding capacity of each layer, were tested for correlation with various measures of grain boundary structure and/or mechanical properties. It was found that certain measures of the atomistic stress distribution correlate strongly with the first-layer binding free energy for substitutional carbon atoms, while common grain boundary identifiers such as sigma value and energy density are not useful in this regard. Preliminary analysis of the more complex case of interstitial oxygen segregation showed that similar measures based on atomistic stress also may be useful here,more » but more systematic correlative studies are needed to develop a comprehensive picture.« less
Authors:
;  [1]
  1. Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)
Publication Date:
OSTI Identifier:
22494838
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 9; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ADSORPTION; CARBON; COMPUTERIZED SIMULATION; ENERGY DENSITY; FREE ENERGY; GRAIN BOUNDARIES; IMPURITIES; ISOTHERMS; LAYERS; MECHANICAL PROPERTIES; MONTE CARLO METHOD; OXYGEN; SEGREGATION; SILICON; STRESSES