Operating at 80, 120, and 200 kV Energy Resolution < 0.5 eV Analytical chemical analysis
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OUTLINE INTRODUCTION
Resolving Power of Microscopes
Transmission Electron Microscope
Useful Signals Generated from Electron–Matter Interaction
Major Contrast Mechanisms for imaging Mass thickness contrast, Diffraction contrast, Phase contrast (HRTEM).
It is essential that specimens for TEM be extremely thin, i.e, a few tens of nms or less, so as for the energetic electron beam to penetrate and generate useful signals. 8
Modes of Imaging Scanning Microscopy Full Frame Imaging Scanning electron microscopy Scanning transmission electron microscopy Focused Ion Beam
diffraction mode (left), imaging mode (right). Shown here are simplified ray diagrams of both modes.
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Bright-field and Dark-field Imaging in TEM BF
DF
DF
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Bright-field vs Dark-field Imaging
To identify grain size and distribution in the microstructure
Nanocrystalline Al. Scale markers are 500 nm.
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Bright-field vs Dark-field Imaging
To identify a second phase in the microstructure Nitrided ferrite in 17-7 PH Stainless Steel
High-resolution TEM (HRTEM)
A HRTEM image of an interface between a Cu particle and alumina grain.
Grain Boundary
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Electron Diffraction Analyze the Lattice Spacing and Orientation
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Convergentbeam electron diffraction (CBED)
3.620 Å
ZA [323]
HOLZ lines used for lattice parameter 3.620 Å determination
3.622 Å
ZA [221]
3.624 Å
Austenitic stainless steel
ZA [111]
ZA [536]
MEASURED SAMPLE THICKNESS FROM AUSTENITIC STAINLESS STEEL Simulated
Simulated
Experimental
ENERGY-FILTERED TEM (EFTEM) IMAGING
Zero-loss EFTEM images: Dislocations in 316 Stainless Steel after Low-temperature Gas-phase Carburization. Specimen prepared by electropolishing
Un-Filtered
Zero-loss Image
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EFTEM Images from Co-Polymer Polystyrene and PVDF Zero loss Image
20 eV Loss Image*
With F Without F
* Energy of plasmon excitation for Fluorine
OUTLINE
TRANSMISSION
KIKUCHI DIFFRACTION (TKD): STEM IN A SEM
EBSD VS TKD Bulk material Surface information Tilted to 70° Interaction volume 30-50 nm
Thin TEM foil Can resolve 3-5 nm -20° - 0° tilt Exiting surface structure
70° Tim Maitland and Scott Sitzman Scanning Microscopy for Nanotechnology, Springer
René de Kloe - EDAX
WHY USE TKD? Improved spatial resolution compared to EBSD: 30-50 nm ⇒ 3-5 nm. Actual resolution will depend on sample composition and preparation. Users that have a FIB system together with EDS/EBSD, can carry out this analysis at practically no extra cost.
Carburized Low-alloy Steel (15 nm/step) XEDS
OUTLINE
ASTAR SYSTEM
PRECESSION ELECTRON DIFFRACTION (PED)
ADVANTAGES OF ASTAR
TEM diffraction patterns easier to interpret Less sensitive to sample thickness variations More diffraction spots → higher precision measurements Automated analysis becomes possible
INDEXING TEM DIFFRACTION PATTERNS Stereographic projection (cubic ) 111
Pre-calculated templates
Angular step size ~1° ~ 3000 templates
001
1-11 Correlation index
Acquired pattern
ASTAR ORIENTATION MAPPING Similar results to SEM-EBSD but with much higher spatial resolution. Down to 1 nm with FEG!
SEM image Deformed Ta6V
EBSD map (20-100 nm step size)
TEM map (1-30 nm step size)
Al (9 nm) –TiN (1 nm) multilayer system Al Phase Map
Orientation Map
ASTAR system could both identify the phases and orientations. Note that the Al layers are finely twinned.
ASTAR ORIENTATION MAPPING Quality Map
Orientation Map
40 nm
Gold nanoparticles
OUTLINE
TEM SAMPLE PREPARATION
FISHIONE NANOMILL MODEL 1040
ADVANTAGES OF NANOMILL Low energy ion source (up to 2kV Ar) Removes amorphous and implanted layers
AS-FIBBED TEM FOIL
High-resolution TEM image of Si showing the effect of Ga implantation and surface amorphization on phase contrast imaging
AFTER NANOMILLING
Same specimen after Ga implantation and amorphization removal by the NanoMilling process
SUMMARY TEM can provide information regarding to Structure Defects (dislocations, twins, etc.) Morphology Composition Valence state Orientation
