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Title: In situ investigation of explosive crystallization in a-Ge: Experimental determination of the interface response function using dynamic transmission electron microscopy

The crystallization of amorphous semiconductors is a strongly exothermic process. Once initiated the release of latent heat can be sufficient to drive a self-sustaining crystallization front through the material in a manner that has been described as explosive. Here, we perform a quantitative in situ study of explosive crystallization in amorphous germanium using dynamic transmission electron microscopy. Direct observations of the speed of the explosive crystallization front as it evolves along a laser-imprinted temperature gradient are used to experimentally determine the complete interface response function (i.e., the temperature-dependent front propagation speed) for this process, which reaches a peak of 16 m/s. Fitting to the Frenkel-Wilson kinetic law demonstrates that the diffusivity of the material locally/immediately in advance of the explosive crystallization front is inconsistent with those of a liquid phase. This result suggests a modification to the liquid-mediated mechanism commonly used to describe this process that replaces the phase change at the leading amorphous-liquid interface with a change in bonding character (from covalent to metallic) occurring in the hot amorphous material.
Authors:
; ;  [1] ; ;  [2] ; ; ;  [3] ;  [1] ;  [4]
  1. Centre Énergie, Matériaux, Télécommunications, Institut National de la Recherche Scientifique, 1650 Lionel Boulet boulevard, Varennes, Quebec J3X 1S2 (Canada)
  2. Center for the Physics of Materials, Departments of Physics and Chemistry, McGill University, 801 Sherbrooke St. W., Montreal, Quebec H3A 2K6 (Canada)
  3. Condensed Matter and Materials Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808 (United States)
  4. (Canada)
Publication Date:
OSTI Identifier:
22314379
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 9; Other Information: (c) 2014 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; CRYSTALLIZATION; INTERFACES; LASERS; LIQUIDS; RESPONSE FUNCTIONS; TEMPERATURE DEPENDENCE; TEMPERATURE GRADIENTS; TRANSMISSION ELECTRON MICROSCOPY