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

light source

illumination system

imaging system

specimen

Basic functions of an optical microscopeH.J. Penkalla

Imagingsystem

specimen

Arrangement of the main components at the TEM

illuminationsystem

light (electron)source

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

Gate-width 12,5 nm

A new era in nanoanalysis:

Design of a Focused Ion Beam Workstation FIB

FIB-nanolithography :FIM/TAP - Tips

Nanodevices

Magnetic memory

Test-masks

for EUV-

microscopy

FIB Preparation of TEM lamellae

Contrast enhancement by the use of the objectiveaperture

H.J. Penk

Structure Chemistry

Bonding

High Resolution Transmission Electron Microscopy

plane wave

Transmissionfunction

Fourier-Transformation

Fourier-Transformation

Diffractionpattern

real image

HRTEM

HRTEM:

Nb/Sapphire

Interfaces

Contrast Transfer: Incoherent Imaging System

Rayleigh Criterion

Artifacts?

Specimenphase shift of scattered wave: -π/2

phase shift by defocus: -π/2

Intensity contrast

Spherical Aberration

MagneticLens

GaussianImage Plane

Contrast Transfer Function (CTF)

Scherzer Focus, no damping

Contrast Transfer:

Real Imaging System

Spherical Aberration

MagneticLens

GaussianImage Plane

Lens

P

CS = 0

Image plane

Aberration corrected electron optics

TU DarmstadtEMBL HeidelbergForschungszentrum Jülich

Volkswagen Stiftung

Haider, Rose, Urban et al. Nature 392, 768 (1998)

Hexapole Cs-Corrector

(Rose, Haider)

Example: SrTiO3, calculated images

Structuremodel

withoutcorrector

Cs-corrector,Cs = + 40 µm

Cs-corrector, Cs = - 40 µm, changes in oxygen sublattice

Jia, Lentzen, Urban, Science 299 (2003)

Twin Boundaries inBaTiO3

Jia and Urban, Science 303 (2004)

CsxNb2.54W2.46O14

Focal-series reconstruction of the object exit-plane wave function

Phase image = projected potential for thin object

Th. Weirich

J. Barthel, A. Thust (ER-C)

G. Cox, H. Hibst(BASF)

aa

bb

averaged phase image+ p2gg symmetry correction

projected crystal structure

CsxNb2.54W2.46O14

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

h ν

( 2 ) E k i n

( 1 ) E 0 - Δ E ,

D

= E B + E k i n

E 0

E Δ

Inelastic Scattering: Analytical Information

Schematical Energy Loss Spectrum

h ν

( 2 ) E k i n

( 1 ) E 0 - Δ E ,

D

= E B + E k i n

E 0

E Δ

B

Energy Loss Spectrometer(magnetic prism)

The Omega Energy Filter

CondensorSystem(KöhlerIllumination)AnalyticalObjective Lens

First ProjectorSystem

Imaging½-Spectrometer

SecondProjectorSystem

ViewingChamber

ElectronDetectorand Camera

Energy SelectingSlit

EucentricGoniometer

Cathode

Energy Filter

Specimen

ImagingΩ−Spectrometer

Energy selectingslit

The Gatan Imaging Filter

Elemental Distribution Images:

Three Window Technique