Confined in-fiber solidification and structural control of silicon and silicon−germanium microparticles
Name
Fink_Confined in-fiber.pdf
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2.05 MB
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Adobe PDF
Checksum (MD5)
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Author(s)
Abouraddy, Ayman F.
Gumennik, Alexander
Levy, Etgar Claude
Grena, Benjamin Jean-Baptiste
Hou, Chong
Rein, Michael
Joannopoulos, John
Fink, Yoel
Date Issued
July 2017
Journal
Proceedings of the National Academy of Sciences
Publisher
National Academy of Sciences (U.S.)
Citation
Gumennik, Alexander et al. “Confined in-Fiber Solidification and Structural Control of Silicon and Silicon−germanium Microparticles.” Proceedings of the National Academy of Sciences 114, 28 (June 2017): 7240–7245 © National Academy of Sciences
Version
Final published version
Abstract
Crystallization of microdroplets of molten alloys could, in principle, present a number of possible morphological outcomes, depending on the symmetry of the propagating solidification front and its velocity, such as axial or spherically symmetric species segregation. However, because of thermal or constitutional supercooling, resulting droplets often only display dendritic morphologies. Here we report on the crystallization of alloyed droplets of controlled micrometer dimensions comprising silicon and germanium, leading to a number of surprising outcomes. We first produce an array of silicon - germanium particles embedded in silica, through capillary breakup of an alloy-core silica-cladding fiber. Heating and subsequent controlled cooling of individual particles with a two-wavelength laser setup allows us to realize two different morphologies, the first being a silicon - germanium compositionally segregated Janus particle oriented with respect to the illumination axis and the second being a sphere made of dendrites of germanium in silicon. Gigapascal-level compressive stresses are measured within pure silicon solidified in silica as a direct consequence of volume-constrained solidification of a material undergoing anomalous expansion. The ability to generate microspheres with controlled morphology and unusual stresses could pave the way toward advanced integrated in-fiber electronic or optoelectronic devices.
MIT Department
Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies
Massachusetts Institute of Technology. Department of Materials Science and Engineering
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Research Laboratory of Electronics
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DOI of Published Version
http://dx.doi.org/10.1073/PNAS.1707778114
