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Title: Structural transformations in amorphous ↔ crystalline phase change of Ga-Sb alloys

Ga-Sb alloys with compositions ranging between ∼12 and 50 at. % Ga are promising materials for phase change random access memory applications. The short-range structures of two such alloys with compositions Ga{sub 14}Sb{sub 86} and Ga{sub 46}Sb{sub 54} are investigated, in their amorphous and crystalline states, using {sup 71}Ga and {sup 121}Sb nuclear magnetic resonance spectroscopy and synchrotron x-ray diffraction. The Ga and Sb atoms are fourfold coordinated in the as-deposited amorphous Ga{sub 46}Sb{sub 54} with nearly 40% of the constituent atoms being involved in Ga-Ga and Sb-Sb homopolar bonding. This necessitates extensive bond switching and elimination of homopolar bonds during crystallization. On the other hand, Ga and Sb atoms are all threefold coordinated in the as-deposited amorphous Ga{sub 14}Sb{sub 86}. Crystallization of this material involves phase separation of GaSb domains in Sb matrix and a concomitant increase in the Ga coordination number from 3 to 4. Results from crystallization kinetics experiments suggest that the melt-quenching results in the elimination of structural “defects” such as the homopolar bonds and threefold coordinated Ga atoms in the amorphous phases of these alloys, thereby rendering them structurally more similar to the corresponding crystalline states compared to the as-deposited amorphous phases.
Authors:
;  [1] ; ;  [2] ;  [3] ;  [4]
  1. Department of Chemical Engineering and Materials Science, University of California, Davis, California 95616 (United States)
  2. Center of Interdisciplinary Magnetic Resonance, National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310 (United States)
  3. Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley, California 20015 (United States)
  4. IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States)
Publication Date:
OSTI Identifier:
22266096
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 114; Journal Issue: 23; Other Information: (c) 2013 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; 36 MATERIALS SCIENCE; ALLOYS; AMORPHOUS STATE; ANTIMONY 121; COMPARATIVE EVALUATIONS; COORDINATION NUMBER; CRYSTALLIZATION; CRYSTALS; GALLIUM 71; GALLIUM ANTIMONIDES; NUCLEAR MAGNETIC RESONANCE; SYNCHROTRONS; TRANSFORMATIONS; X-RAY DIFFRACTION