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Title: Strain effects and intermixing at the Si surface: Importance of long-range elastic corrections in first-principles calculations

Here we investigate Ge mixing at the Si(001) surface and characterize the 2 N Si(001) reconstruction by means of hybrid quantum and molecular mechanics calculations (QM/MM). Avoiding fake elastic dampening, this scheme allows to correctly take into account long range deformation induced by reconstructed and defective surfaces. We focus in particular on the dimer vacancy line (DVL) and its interaction with Ge adatoms. We first show that calculated formation energies for these defects are highly dependent on the choice of chemical potential and that the latter must be chosen carefully. Characterizing the effect of the DVL on the deformation field, we also find that the DVL favors Ge segregation in the fourth layer close to the DVL. Using the activation-relaxation technique (ART nouveau) and QM/MM, we show that a complex diffusion path permits the substitution of the Ge atom in the fourth layer, with barriers compatible with mixing observed at intermediate temperature. We also show that the use of QM/MM results in much more signi cant corrections at the saddle points (up to 0.5 eV) that at minima, demonstrating its importance for describing kinetics correctly.
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. Univ. de Montreal, Quebec (Canada). Dept de Physique; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
  2. Univ. of Grenoble Alpes, Grenoble (France)
  3. Univ. of Grenoble Alpes, Grenoble (France); Alternative Energies and Atomic Energy Commission (CEA) and Institute for Nanoscience and Cryogenics (INAC), Grenoble (France). Atomistic Simulation Lab
  4. Univ. Pierre and Marie Curie, Paris (France). Lab of Theoretical Condensed Matter Physics; Univ. de Montreal, Quebec (Canada). Dept de Physique
Publication Date:
OSTI Identifier:
1185571
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 90; Journal Issue: 15; Journal ID: ISSN 1098-0121
Publisher:
American Physical Society (APS)
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Natural Science and Engineering Research council of Canada
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS