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Title: Amorphization of hard crystalline materials by electrosprayed nanodroplet impact

A beam of electrosprayed nanodroplets impacting on single-crystal silicon amorphizes a thin surface layer of a thickness comparable to the diameter of the drops. The phase transition occurs at projectile velocities exceeding a threshold, and is caused by the quenching of material melted by the impacts. This article demonstrates that the amorphization of silicon is a general phenomenon, as nanodroplets impacting at sufficient velocity also amorphize other covalently bonded crystals. In particular, we bombard single-crystal wafers of Si, Ge, GaAs, GaP, InAs, and SiC in a range of projectile velocities, and characterize the samples via electron backscatter diffraction and transmission electron microscopy to determine the aggregation state under the surface. InAs requires the lowest projectile velocity to develop an amorphous layer, followed by Ge, Si, GaAs, and GaP. SiC is the only semiconductor that remains fully crystalline, likely due to the relatively low velocities of the beamlets used in this study. The resiliency of each crystal to amorphization correlates well with the specific energy needed to melt it except for Ge, which requires projectile velocities higher than expected.
Authors:
; ;  [1] ;  [2]
  1. Department of Mechanical and Aerospace Engineering, University of California, Irvine, California 92697 (United States)
  2. Laboratory for Electron and X-ray Instrumentation, Calit2, University of California, Irvine, California 92697 (United States)
Publication Date:
OSTI Identifier:
22402599
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 17; 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; AGGLOMERATION; AMORPHOUS STATE; COVALENCE; GALLIUM ARSENIDES; GALLIUM PHOSPHIDES; INDIUM ARSENIDES; LAYERS; MONOCRYSTALS; PHASE TRANSFORMATIONS; QUENCHING; SEMICONDUCTOR MATERIALS; SILICON; SILICON CARBIDES; SURFACES; THICKNESS; TRANSMISSION ELECTRON MICROSCOPY; VELOCITY