Instrumentation: Transmission Electron Microscopy
Knoll and Ruska (1932)
the first Transmission Electron Microscope
Contents:
1. Introduction
2. Sources
3. Lenses
4. Spectrometers and Filters
5. STEM
6. Advanced Instrumentation
imaging system
specimen
illumination system
light source
Basic functions of an optical microscope
H.J. Penkalla
light (electron)
source
illumination
system
specimen
Imaging
system
Arrangement of the main components at the TEM
H.J. Penkalla
Electron Beam Sources: Thermal Emitter
Electron Beam Sources: Field-Emitter
Lens Aberrations:
Spherical and Chromatic Aberration
Specimen preparation: ion beam thinning
2.5 - 4.0 kV
Specimen preparation:
electroytical jet thinning
Specimen preparation:
ultramicrotomy
Specimen preparation: carbon replica
A new era in nanoanalysis:
Gate-width 12,5 nm
Design of a Focused Ion Beam Workstation FIB
FIB-nanolithography :
Nanodevices
FIM/TAP - Tips
Test-masks
for EUVmicroscopy
Magnetic memory
FIB Preparation of TEM lamellae
Contrast enhancement by the use of the objective
aperture
H.J. Penk
Structure
Chemistry
Bonding
High Resolution Transmission Electron Microscopy
plane wave
HRTEM
Transmission
function
FourierTransformation
Diffraction
pattern
FourierTransformation
real image
HRTEM:
Nb/Sapphire
Interfaces
Contrast Transfer: Incoherent Imaging System
Rayleigh Criterion
Artifacts?
Specimen
phase shift of
scattered wave: -π/2
phase shift by
defocus: -π/2
Intensity contrast
Spherical Aberration
Magnetic
Lens
Gaussian
Image Plane
Contrast Transfer Function (CTF)
Scherzer Focus, no damping
Contrast Transfer:
Real Imaging System
Spherical Aberration
Magnetic
Lens
Gaussian
Image Plane
Aberration corrected electron optics
Lens
CS = 0
P
Image plane
¾ TU Darmstadt
¾ EMBL Heidelberg
¾ Forschungszentrum Jülich
Volkswagen Stiftung
Haider, Rose, Urban et al.
Nature 392, 768 (1998)
Hexapole Cs-Corrector
(Rose, Haider)
Example: SrTiO3, calculated images
Structure
model
without
corrector
Cs-corrector,
Cs = + 40 µm
Cs-corrector, Cs = - 40 µm, changes in oxygen sublattice
Jia, Lentzen, Urban, Science 299 (2003)
Twin Boundaries in
BaTiO3
Jia and Urban, Science 303 (2004)
CsxNb2.54W2.46O14
Focal-series reconstruction of the object exit-plane wave function
Th. Weirich
J. Barthel, A.
Thust (ER-C)
G. Cox, H. Hibst
(BASF)
Phase image = projected potential for thin object
CsxNb2.54W2.46O14
b
a
averaged phase image
+ p2gg symmetry correction
projected crystal structure
Th. Weirich, J. Barthel, A. Thust (ER-C), G. Cox, H. Hibst (BASF)
Structure
Chemistry
Bonding
Analytical TEM: Electron Intensity Distribution
Inelastic Scattering, low energy losses:
phonon and plasmon excitation
Inelastic Scattering: Analytical Information
D
E0
hν
(2) Ekin
(1) E0 - Δ E,
Δ E = EB + Ekin
Schematical Energy Loss Spectrum
D
E0
hν
(2) Ekin
(1) E0 - Δ E,
Δ E = EB + Ekin
Energy Loss Spectrometer
(magnetic prism)
B
The Omega Energy Filter
Cathode
Condensor
System
(Köhler
Illumination)
Analytical
Objective Lens
First Projector
System
Imaging
Imaging
½-Spectrometer
Ω−Spectrometer
Second
Projector
System
Viewing
Chamber
Electron
Detector
and Camera
Specimen
Eucentric
Goniometer
Energy Filter
Energy Selecting
Energy
selecting
Slit
slit
The Gatan Imaging Filter
Elemental Distribution Images:
Three Window Technique