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Title: Extended X-ray absorption fine structure investigation of Sn local environment in strained and relaxed epitaxial Ge{sub 1−x}Sn{sub x} films

We present an extended X-ray absorption fine structure investigation of the local environment of Sn atoms in strained and relaxed Ge{sub 1−x}Sn{sub x} layers with different compositions. We show that the preferred configuration for the incorporation of Sn atoms in these Ge{sub 1−x}Sn{sub x} layers is that of a α-Sn defect, with each Sn atom covalently bonded to four Ge atoms in a classic tetrahedral configuration. Sn interstitials, Sn-split vacancy complexes, or Sn dimers, if present at all, are not expected to involve more than 2.5% of the total Sn atoms. This finding, along with a relative increase of Sn atoms in the second atomic shell around a central Sn atom in Ge{sub 1−x}Sn{sub x} layers with increasing Sn concentrations, suggests that the investigated materials are homogeneous random substitutional alloys. Within the accuracy of the measurements, the degree of strain relaxation of the Ge{sub 1−x}Sn{sub x} layers does not have a significant impact on the local atomic surrounding of the Sn atoms. Finally, the calculated topological rigidity parameter a** = 0.69 ± 0.29 indicates that the strain due to alloying in Ge{sub 1−x}Sn{sub x} is accommodated via bond stretching and bond bending, with a slight predominance of the latter, in agreement with ab initiomore » calculations reported in literature.« less
Authors:
;  [1] ;  [2] ;  [3] ; ;  [1] ;  [2] ; ;  [1] ;  [4] ; ;  [5]
  1. imec, Kapeldreef 75, 3001 Leuven (Belgium)
  2. (Belgium)
  3. Laboratory for Solid State Physics and Magnetism, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium)
  4. Dutch-Belgian Beamline (DUBBLE), ESRF - The European Synchrotron, CS 40220, 38043 Grenoble (France)
  5. Instituut voor Kern- en Stralingsfysica, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium)
Publication Date:
OSTI Identifier:
22413232
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; 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:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION; ATOMS; CONCENTRATION RATIO; COVALENCE; DIMERS; ELECTRONIC STRUCTURE; EPITAXY; FILMS; FINE STRUCTURE; GERMANIUM; INTERSTITIALS; LAYERS; RELAXATION; STRAINS; TIN; VACANCIES; X RADIATION