Advanced FE-SEM: from Nano-imaging to Chemical and Structural Analyses

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Advanced FE-SEM from Nano-imaging to Chemical
and Structural Analyses

• Chi Ma
• Division Analytical Facility
• Division of Geological and Planetary Sciences,
  Caltech
• chi_at_gps.caltech.edu
• http//www.gps.caltech.edu/facilities/analytical/

CSEM 2003
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A high-resolution analytical scanning electron
microscope (LEO 1550VP) was installed in Sept
2002 at Caltech GPS Division Analytical Facility
and became available for campus-wide use in Dec
2002. The new PC-based LEO 1550 SEM is a
multipurpose state-of-the-art instrument capable
of SE, BSE, variable pressure SE, CL imaging,
high-resolution imaging (down to 1 nm), chemical
and crystallographic analyses. This is a field
emission SEM which can operate at voltages
ranging from 200 V to 30 kV and at magnifications
ranging from 20 x to 900 kx for a wide variety of
applications.  The 1550 is equipped with two
state-of-the-art accessories.  The first, an
Oxford energy-dispersive X-ray spectrometer
(EDS), can determine and map the elemental
distribution within a region or along a line, or
perform a quantitative chemical analysis of a
point or region.  The other accessory, a HKL
electron backscatter diffraction system (EBSD),
can determine the crystal structure and
orientation of the sample at a specific point,
and conduct orientation mapping and phase
identification at submicron scale. The SEM was
acquired and is supported in part by the MRSEC
program of the NSF under DMR-0080065.
CSEM 2003
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The analytical SEM is having a wonderful impact
on campus. Since Dec 2002, about 85 users from
40 faculty research groups on campus and JPL have
used the SEM. They are from
Material Sciences EE, ME, CS Applied
Physics Aero-engineering Bio-engineering
Biology Chemistry Chemical Engineering Physics
Geology Geochemistry Geophysics Geobiology
CSEM 2004
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Imaging Capabilities (5 electron detectors)

• High resolution Imaging In-Lens SE1
• Low Voltage Imaging (200V 5kV) better surface
  imaging due to reduced beam penetration
• Compositional Contrast Imaging - BSE
• Orientation Contrast Imaging FSE
• Variable Pressure SE Imaging (3Pa-100Pa)
• Cathodoluminescence Imaging
• STEM imaging

CSEM 2003
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Chemical Analysis - EDS

• Detector capable of detecting Be to U
• Quantitative EDS analysis - Quantitative results
  with a relative accuracy of better than 5 and
  detection limits of better than 0.5 can be
  readily obtained.
• X-ray mapping

Structural Analysis - EBSD

• Orientation mapping texture analysis
• Phase ID

CSEM 2003
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Imaging, EDS and EBSD analyses at same time
CSEM 2003
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BSE image showing chemical variation of micas
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CL image of benitoite
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STEM (left) and SE (right) images of borosilicate
fibers