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Title: Thermodynamic and morphological analysis of large silicon self-interstitial clusters using atomistic simulations

We study computationally the formation of thermodynamics and morphology of silicon self-interstitial clusters using a suite of methods driven by a recent parameterization of the Tersoff empirical potential. Formation free energies and cluster capture zones are computed across a wide range of cluster sizes (2 < N{sub i} < 150) and temperatures (0.65 < T/T{sub m} < 1). Self-interstitial clusters above a critical size (N{sub i} ∼ 25) are found to exhibit complex morphological behavior in which clusters can assume either a variety of disordered, three-dimensional configurations, or one of two macroscopically distinct planar configurations. The latter correspond to the well-known Frank and perfect dislocation loops observed experimentally in ion-implanted silicon. The relative importance of the different cluster morphologies is a function of cluster size and temperature and is dictated by a balance between energetic and entropic forces. The competition between these thermodynamic forces produces a sharp transition between the three-dimensional and planar configurations, and represents a type of order-disorder transition. By contrast, the smaller state space available to smaller clusters restricts the diversity of possible structures and inhibits this morphological transition.
Authors:
;  [1] ;  [2]
  1. Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)
  2. Siltronic AG, Hanns-Seidel-Platz 4, D-81737 München (Germany)
Publication Date:
OSTI Identifier:
22399411
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 13; 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; ATOMIC CLUSTERS; COMPUTERIZED SIMULATION; CRITICAL SIZE; DISLOCATIONS; FORMATION FREE ENERGY; INTERSTITIALS; ION IMPLANTATION; MORPHOLOGY; ORDER-DISORDER TRANSFORMATIONS; POTENTIALS; SILICON; TEMPERATURE DEPENDENCE; THERMODYNAMICS; THREE-DIMENSIONAL LATTICES