PY5019 – UltramicroscopyTransmission Electron Microscopy
Dr Hongzhou [email protected]
Office: SNIAM 1.06Tel: 896 4655Tel: 896 4655
School of PhysicsTrinity College Dublin
There’s plenty of room at the bottomThere s plenty of room at the bottom
Richard Feynman, 1960• “with the greatest care and effort, it
can only resolve about 10 angstroms.”• “It is very easy to answer many ofIt is very easy to answer many of
these fundamental biological questions; you just look at the thing!”
• “What you should do in order for us toWhat you should do in order for us to make more rapid progress is to make the electron microscope 100 times better”
• Is there no way to make the electron microscope more powerful?
ContentContent• Transmission Electron Microscopy• Alternative Types of EMs
– Emission Electron MicroscopyR fl ti El t Mi– Reflection Electron Microscopy
– Mirror Electron Microscopy– Scanning Electron MicroscopyScanning Electron Microscopy
• X‐Ray and EELS Microanalysis• Scanning‐Probe MicroscopyScanning‐Probe Microscopy• Focused‐ion Beam• Helium‐ion Microscopy• Helium‐ion Microscopy
ContentContent
• Introduction• The Instrument• Electron‐Specimen Interaction• Diffraction• Diffraction Contrast• Phase Contrast• EDXEELS• EELS
• SEM‐HIM
TextbooksTextbooks
• David Williams and Barry Carter, Transmission Electron dMicroscopy, 2nd Edition, Springer
• Ludwig Reimer, Transmission Electron Microscopy, 5thEdition, Springer
• L. M. Peng, S. L. Dudarev, M. J. Whelan, High‐energy Election Diffraction and Microscopy, Oxford Science Publications
• Brent Fultz, James M. Howe, Transmission Electron Microscopy and Diffraction of Materials, Springer
• J. W. Edington, Practical Electron Microscopy in MaterialsJ. W. Edington, Practical Electron Microscopy in Materials Science, The MacMillan Press, LTD
• Marc De Graef, Introduction to Conventional Transmission Electron Microscopy CambridgeElectron Microscopy, Cambridge
MarkingMarking• Attendance (8%)• An essay (20%)An essay (20%)
– Something about your research and the cutting‐edge electron/ion microscopy– Not limited to the materials we cover in this module
• Two sets of homework (20%)– Lecture 4 (due at lecture 5): Find a paper… – Lecture 8 (due at lecture 9)
• Interview (20%)– 15 min my office (SNIAM 1 06)– 15 min, my office (SNIAM 1.06)– You choose a relevant topic (different from your essay) and we discuss it– Please send me the topic and arrange a time with me by Lecture 6, and we will
finish it before Christmas breakQ i ( i ht 5 i b k i b f l C l l t ) 32%• Quiz (eight 5‐min open‐book quizzes before class, Calculators): 32%– How fast can you write?– How fast can you find the answer?
Lecture One: IntroductionLecture One: Introduction
• Something about the TEMg• Brief history of TEM development• Electrons: the very basics for the TEM• Introduction of TEM modes• Examples of TEM Characterization• Applications of the TEM• Limitations of the TEMC h d f d• Current research and future trends
• Resources
TEM ‐ Overview• TEM Extremely Expensive:
– Basic configuration: € 4/eVg– With options: €9/eV (FEI Titan: €2.7M)– FE costs twice as much as Thermionic source
• Different Forms: HRTEM, STEM, AEM, etc– Routine instruments: 100‐200 kV– Medium (Intermediate) –voltage (IVEM): 200‐500 kV– High‐voltage (HVEM): 500 kV‐ 3MV
l h l l l l• Advantages and applications: High Spatial and Analytical Resolution with Completely Quantitative Understanding– Structural and chemical information
A range of spatial range: atomic scale nano micrometre– A range of spatial range: atomic scale – nano – micrometre– Atomic resolution– Quantitative information– In‐situ capabilityIn situ capability
• How can we do it? – Instrumentation: Fundamental Physics of electrons & Electron Optics– Signal generation: Electron‐sample interactiong g p– Signal detection: modes– Operation and interpretation
Historical DevelopmentE l DEarly Days
Louis de Broglie: Wave nature of
Knoll&Ruska:Electron Microscope
Wave nature of electrons Siemens&Halske: Regular
Production of TEM, 7nmKossel/Mollenstedt:
El Diff i i TEM
1925
27
33
1932
36 39
Electron Diffraction in TEMs
45Hitachi JEOL Philips FEI
Commercial TEM: Metropolitan‐Vickers EM1
Hitachi, JEOL, Philips, FEI, Carl Zeiss: Widely available
Davisson&Germer; Thomson&Reid
light microscope Resolution limit surpassed
;Electron diffraction
Busch: Electromagnet/Electrostatic focused electrons
Historical Development
y
Diffraction Kinematical/Dynamical
Theory
Analytical Cs correctedMonochromatorTEM, SAED, EDX
Sub‐eV, sub‐A
Early DaysFeynman’s talk
Cambridge, Hirsch&Howie
1945
1956
1970
1980
1990
20001956
HRTEMField Emission
Cowley, multislice
STEM, EELS, Holographmultislice
Key Events in the History of Electron Microscopy, DOI: 10.1017/S1431927603030113
Resolution… …
1.0Siemens, UM100
0.8
)
0.4
0.6
olut
ion
(nm
)
0.2
Res
o
JEM 100CXJEM 200CX
JEOL 2010
Tecnai F30Cs corrected
1950 1960 1970 1980 1990 2000 2010
0.0Titan and TEAM
1950 1960 1970 1980 1990 2000 2010
Year
Nobel Prizes• Karl Manne Georg Siegbahn: 1924 in PhysicsKarl Manne Georg Siegbahn: 1924 in Physics
– “for his discoveries and research in the field of X‐ray spectroscopy”• Denis Gabor: 1971 in Physics
– “for his invention and development of the holographicmethod”for his invention and development of the holographicmethod• Albert Claude, Christian de Duve, George E. Palade: 1974 in
Physiology or Medicine– “for their discoveries concerning the structural and functional
organization of the cell”• David Baltimore, Renato Dulbecco, Howard Martin Temin: 1975 in
Physiology or Medicine“for their discoveries concerning the interaction between tumour viruses– for their discoveries concerning the interaction between tumour viruses and the genetic material of the cell”
• Aaron Klug: 1982 in Chemistry– “His development of crystallographic electron microscopy and hisHis development of crystallographic electron microscopy and his
structural elucidation of biologically important nucleic acid‐protein complexes”
• Ernst Ruska; Gerd Binnig, Heinrich Rohrer(STM): 1986 in Physics“hi f d l k i l i d f h d i f h fi– “his fundamental work in electron optics, and for the design of the first electron microscope”
Why Electrons?• Image resolution/resolving power• Image resolution/resolving power
– Naked eyes: 0.1‐0.2 mm– Magnification (100,000X) – resolution (1 nm)– Rayleigh criterion (VLM):
• 550 nm – 300 nm resolution
sin61.0
n
– TEM Atomic‐resolution• Electron wavelength:
– 100keV – 0.004nm– 1960s High‐voltage EM
• Poor electron lens, but electrons can be focused :
sinn
pm4~22.12/1E
(1pm =10‐12 m)
(1 nm = 10‐9 m)
– Small aperture required: 10‐25 mrad (resolution: 0.1‐0.3nm)– Electron Probe (spatial resolution/sensitivity)
» Typically < 5 nm, at best < 0.1nm (Cs)» Higher currents (Cs)
• Information limit: Partial Spatial& temporal Coherence: E: 0.3‐2eV• Spherical &chromatic aberration Corrections (resolution: <0 1 nm) thin sample• Spherical‐&chromatic aberration Corrections (resolution: <0.1 nm), thin sample• Focal Series Reconstruction/holography
• Electrons, ionizing radiation: Strong Interactions– Wide range of 2nd signals:
• Chemical information (AEM: XEDS, EELS )‐ Composition and distribution( , ) p• EFTEM for band‐gap/chemical bond imaging(Cc)
• Materials:– Metals, alloys, ceramics, glasses, polymers, semiconductors, composite mixtures, wood,
textiles, concreteB lk ti l fib t t– Bulk, particles, fibers, nanostructures
– Nanoscale Materials and Devices– Biomaterials, bio‐inorganic interface
The System and the equationThe system:
• Solid: nuclei and atomic electrons • Solid: nuclei and atomic electrons• High‐energy electrons
Ht
i
‐ A closed system:
tEEi sexp‐ Time independent (definite energy):VTH
‐ The Hamiltonian: crnj HRRrrrVm
H ...)......;...;(2 11
22
Di ti i h bl h ff t i d
pp ( gy)
sEEH
nnj
eeZRRrrrV22
11 41...)......;...;(
‐ Distinguishable: exchange effects ignored• Fermi Velocity of atomic electrons ~ 106 m/s• Velocity of beam electrons ~ 0.5c – 0.99 c (108 m/s)
j jn nnj rrRr0
11 4);;(
‐ Elastic scattering: the solid does not change its states rRRrrRRrrr nini .........;............;...; 1111 .........;............;... 1111 nisnicr RRrrERRrrH
‐ The one‐body equation for the incident electrons:‐ The one‐body equation for the incident electrons:
‐ The relativistic invariance• Dirac equation should be used
rErrVm
)(
22
2
n n
njinj Rr
eZdrrrredRdrRRrrrVrV
22
011 '
')'(
41...)......;...;(*)(
20mm kEmEE 1
20
20
Dirac equation should be used
• Diffraction: Neglect effects associated with the spin of electrons• The relativistic Klein‐Gordon equation
rcm
EmmErH
2
0
0
21
2
2
1cv
mcmmEE
221 2
0
Electron‐Optical Refractive Index and the Schrodinger Equation
Electron‐optical Refractive Index: vn
Time‐independent wave equation: 022 rkr m
nkk 2Electron optical Refractive Index:
mmvn
12 E
h2
nkkm
m
Emh
02
Non‐relativisticRelativistic
00 212 E
EEm kev511200 cmE
2/1
20
20
22
EEE
VEEVErnm
A V( ) E
022
02
rVEmr
VEmVEm
hk
mm
0
0
2222
Assume: V(r) << E
...2
)(12
)(212
222
0
0
2/1
20
0
2/1
20
2200
EEEE
ErV
EEEVEE
EEEVEVEVEEErn
022
2)(1 22
20
0
02
rc
EEEEEEE
ErVr
02)(2 22002
r
cEEE
ErVEEr
In the vacuum: EIn the material: E-V(r)
rZeeZre ff222 )()'(1
021)(2
1 220
00
2
r
cE
EErV
EEEr
021)(
22
220
00
02
rcE
EErV
EEEEEr
E
rrZe
RreZdr
rrrerV eff
n n
n
00 4)(
'')(
41)(
00 c
000 1
EEmmm
0
0
0
0
0
0
00
02
0
0
22
22
21
21
EEEEE
EEE
EEEE
EE
EEEE
cmE
mmEE
021)(22
20
00
02
rmEErV
EEEEEr
Why can we use k and for electrons?
kAemvp
• k and are not uniquely defined quantities(not observable quantities)
A i i l d fi d A A A’ A’ 0 (B A)
sdAeldvmldAevm
1112
A is not uniquely defined: A = A+A’, A’= 0 (B= A)Interference, phase difference
S 12
dkikzkA exp)(• A limited wave packet rkikAr exp)()(
Use infinite extension plane wave for the centre of the
k
ikzexp
centre of the spectrum: kk
ikzexp0
Some comments on Electrons in TEMSome comments on Electrons in TEM
• Single electronI 9 l /– Beam current: I = 1 nA = 6.25 x 109 electrons/s
• Up to 0.1‐ 1 uA– Linear density: Assume regular interval emission
• ne = I/v = (6.25 x 109 /v) electrons/(nA m)– 100 keV: v = 0.5c =1.5x108 m/s; ne ~ 50 electrons/(nA m)– Separating (0.1 uA = 100 nA): s = 1/(ne I) = 1/(50*100)~ = 0.2 mm
• Stationary atoms and lattice vibration:– 100 nm sample: t = 1 x 10‐7 m/(1 6X108 m/s ) ~5x10‐16 s– 100 nm sample: t = 1 x 10 m/(1.6X10 m/s ) 5x10 s– Lattice vibration: ~ 10‐12 s– Time interval between two electrons (at 1 nA): 0.02m/(1.6x108 m/s) = 10‐10 s:
the atom have gone through 100 cycles, no correlation between atomic position for consecutive electronsposition for consecutive electrons
• Duality– Non‐relativistic:– Relativistic (> 100eV): p
h 2/1
02 eVmh
h 2/1
20
0 212
cmeVeVm
TEMs Modesl i• Elastic– Coherent
• Diffraction contrast: Bright‐field, Dark field, weak beamPh l i
• Conventional TEM• Scanning Transmission Electron Microscopy (STEM)
• Phase contrast: lattice resolving, High resolution TEM (HRTEM)
• Selected Area electron Diffraction (SAD)
• Lorentz Microscopy• Analytical electron microscopy (AEM)
– X‐ray Energy‐dispersive Spectromtry(XEDS) : 0 1‐ 1um• Large‐angle Convergent‐
beam electron diffraction (CBED)?
– Incoherent • Z‐contrast: High‐angle
Spectromtry(XEDS) : 0.1 1um– Electron energy‐loss spectrometry (EELS)
• Relatively ‘New’l l hZ contrast: High angle
annular dark‐field (HAADF)
• Inelastic– Energy‐Filtering TEM
(EFTEM): 0.3‐0.5 nm
– Electron Magnetic Circular Dichroism(EMCD)– Electron vortex– Electron Holography (no lens): electron (EFTEM): 0.3 0.5 nm
– Energy‐dispersive x‐ray spectroscopy (EDS)
– Electron energy‐loss spectroscopy (EELS)
g p y ( )biprism, Aharonov‐Bohm effect– In‐situ Microscopy
spectroscopy (EELS)
Instrumentation/Techniques/Signal generation and detection/Interpretation
Diffraction ‐ SAED
Phase, crystallographic orientation, order disorder, defects
Diffraction ‐ CBEDDiffraction CBED
• Specimen thickness• Full 3D symmetry • Lattice‐strainE ti hi d• Enantiomorphism and polarity
• Valence‐electron distribution, structure factors, and chemical bondingg
• Characterization of line and planar defects
Chapter 20‐21, David Williams and C. Barry Carter
Diffraction Contrast – BF and DFDiffraction Contrast BF and DF
Edington, Practical Electron Microscopy in Materials Science
Phase Contrast ‐ HRTEM
AluminiumB: <101>b= ½<110>
Shamsuzzoha, M., et al., Scripta Metallurgica et Materialia, 1990. 24(8): p. 1611‐1615.
Applications: R&D• Low dimensional materials/objects
– Nanostructures– Surfaces and Interfaces
• Catalysis: Automotive/Petroleum– particle size, shape, surface layers/absorbates, reactions
• Image overlap: matrix and precipitatesImage overlap: matrix and precipitates • Sufficient contrast against background noise• Mobile under investigation
• Pharmaceutical– Drug discovery: substances– Understand & characterize molecular targets– Validate the effectsValidate the effects– Contaminations
• Photographic S&T/Paper/Glass/Semiconductor/Mineral/Museum/ForensiS&T/Paper/Glass/Semiconductor/Mineral/Museum/Forensic …
Z.R. Li, “Industrial Application of Electron Microscopy”, Marcel Dekker, INC, 2003
Automotive ApplicationsAutomotive Applications
• Automotive exhaustAutomotive exhaust catalysts: Pt, Pd, Rh– Reduce : hydrocarbons, y ,CO, NOx
– Catalyst Deactivation S diStudies
• Thermal aging: migration/redistribution g /of elements
• Chemical Poisoning
Semiconductor Industry• Failure analysis• Doping contrastp g
Example: Nanotubes/Nanocones
Limitations of the TEM• Sampling: small part of your specimen• Interpreting TEM images
– Projection‐limitation • Transmission 2D image: artefacts• Average through the thicknessAverage through the thickness
– Electron tomography• Beam Damage and Safety: Useful viewing time (Cs?)
– Knock‐ondi l i i i i d– Radiolytic processes: ionisation damage
– Image magnification and beam current density– Solutions:
• Sensitive detector + intense sources: dose• Cryo‐microscopy
• Specimen Preparation – Thinner is Better– Thin Sample: electron transparent (beam energy, Z, resolution desired)
• For 100 keV < 100 nmFor 100 keV < 100 nm• HRTEM: < 50 nm, < 10 nm
– Thinning: artefacts, damages, …• Electropolishing• Ion‐beam etchingg• Ultromicrotomy• Cryofixation
Emerging Trends – Now and the FutureEmerging Trends Now and the Future• Atomic Location and Quantitative imaging
– Comparison: experimental and simulationp p– The Stobbs’ Factor: HRTEM contrast level deviates from simulation
• Quantitative Intensity: contrast level– Thermal diffuse scattering
• Detection and correction of Aberrations• Detection and correction of Aberrations– Higher order objective aberration – Automatic diffractogram analysis
• FSR/Off‐axis EH: Cs 1% accuracy• 3‐fold Astigmatism• 2nd axial coma(beam tilt)• Cs correction: standard imaging conditions
– information limit ~ 1.3A– Probe size ~1A – Image delocalisation
• On‐line microscope control• Environmental EM with in‐situ sample treatment
4 di i l TEM• 4‐dimensional TEM
ResourcesResources
• InternetInternet
• Simulation software packages
l / di• Journals/Proceedings– Proceedings of the International Conferences on
lElectron Microscopy
• Groups/Labs/Consortiums
David Williams and Barry Carter, Transmission Electron Microscopy, 2nd Edition, Springer
EM Books• "Analytical electron microscopy for materials science". D. Shindo, T. Oikawa. Springer (2002). Excellent, up to date, practical . (ELS, EDX, CBED, Alchemi, Sample prep, holography etc).• "High resolution electron microscopy and related techniques". P. Buseck, J.Cowley and L.Eyring, Eds. Oxford Univ Press.(1989). Comprehensive overview.• Electron Backscattering Diffraction in Materials Science, A. J. Schwartz, M. Kumar and B. L. Adams (Eds.) Plenum (New York, 2000) • Atlas of Backscattering Kikuchi Diffraction Patterns D J Dingley, K Z Baba‐Kishi and V Randle IOP (Bristol, 1995)• Introduction to Texture Analysis V Randle and O Engler Gordon and Breach (Amsterdam 2000)• Texture and Anisotropy U F Kocks, C. N. Tomé and H‐R Wenk Cambridge (Cambridge 1998)py , g ( g )• Elastic and Inelastic Scattering in Electron Diffraction and Imaging Z L Wang Plenum (New York 1995)• Introduction to Analytical Electron Microscopy J J Hren, J I Goldstein and D. C Joy (Eds) Plenum (New York 1979)• Principles of Analytical Electron Microscopy D C Joy, A D Romig and J I Goldstein (Eds) Pleum (New York 1986)• Convergent Beam Electron Diffraction of Alloy Phases J Mansfield (Ed) Adam Hilger (Bristol 1984)• Large‐angle convergent beam electron diffraction. J.P. Morniroli. (Society of French Microscopists. Paris). 2002. In english. ISBN 2‐901483‐05‐4• Diffraction Physics. J.M.Cowley. North‐Holland. 3rd Edition. 1990. • Advanced computing in electron microscopy. E.J.Kirkland. Plenum. New York. 1998.• "Transmission Electron Microscopy and Diffractometry of Materials". B. Fultz and J. Howe. Springer. 2001. Excellent coverage of theory and worked examples.py y p g g y p• "Fundamentals of HREM". S. Horiuchi. North Holland. 1994.• "Structural Electron Crystallography" D. L. Dorset, Plenum/Kluwer. 1997. Mainly organics.• "Transmission electron microscopy: A textbook for materials science". D.B.Williams and C.B.Carter. Plenum Press. 1996. Pedagogically sound introductory text. Indispensible.• "High Resolution Electron Microscopy". J.C.H.Spence. Oxford Univ Press. 2003. (3rd Edn). How to do HREM.• Electron energy loss specrtroscopy in the electron microscope. R.F. Egerton. Plenum. New York. 2nd edition 1996.• "Convergent beam electron diffraction IV". M.Tanaka, M.Terauchi, K.Tsuda, K.Saitoh. JEOL Ltd. Tokyo. and earlier volumes. Superb collection of CBED patterns.• "Electron microdiffraction". J.Spence and J.M. Zuo (Plenum, 1992). How to do CBED. Worked example of how to find space‐group of crystal from CBED patterns.• "Electron Diffraction Techniques". Vols 1 and 2. Oxford/IUCr Press. J.Cowley, ed. 1993.• "High resolution electron microscopy for materials science". D.Shindo, K.Hiraga.Springer. 1998. Beautiful collection of HREM images and examples of their analysis.• "Electron Microscopy of thin crystals". P.B.Hirsch et al. Krieger. New York. 1977. Classic text with many worked examples. Indispensible.• "Electron‐diffraction Analysis of Clay Mineral Structures". B. B Zvyagin. Plenum. 1967• "Electron Diffraction Structure Analysis". B. K. Vainshtein. Pergamon. 1964• "Intro. to Scanning Transmission Electron Microscopy", R. J. Keyse, A. J. Garratt‐Reed, P.J. Goodhew and G. W. Lorimer, (BIOS Scientific Publishers, Royal Micros. Soc., 1998)• "Electron Energy Loss Spectroscopy", Rik Brydson, (BIOS Scientific Publishers, Royal Micros. Soc., 2001).• "Transmission Electron Microscopy. 4th edit.", L. Reimer, (Springer‐Verlag 1997). Excellent broad coverage with all the basic physics, including radiation damage. Indispensible.• "Electron Holography", A. Tonomura, (Springer‐Verlag, 1999)• "Introduction to electron holography". E. Voelkl, Ed. (1998). Plenum.• "Practical Electron Microscopy in Materials Science", J. W. Edington (Van Nostrand Reinhold, 1976)• "Electron beam analysis of materials" by M. Loretto. Chapman and Hall. 1984.• "Electron microscopy in heterogeneous catalysis". P. Gai and E. Boyes. Inst Phys. (2003).• "Interpretation of electron diffraction patterns" Andrews, K., Dyson, D., Keown, S. (1971). Plenum New York.• "Crystallography and crystal defects". Reprinted by Techbooks, 4012 Williamsburg Court, Fairfax, Virginia, USA 22032. Extremely useful. Highly recommended.• JCPDS‐ICDD Powder diffraction file. http://www.icdd.com/ . Identify crystalline phases from their diffraction data.• Special issue of Zeitschrift Kirstallographie on electron crystallography. 2003/4. U.Kolb.• Journal of Microscopy and Microanalysis (mid 2003) Special issue on Quantitative Electron Diffraction. J.C.H. Spence, editor.
SummarySummary
• TEM: expensive but powerful techniquesTEM: expensive but powerful techniques
• Electrons: wave/particle duality
i i i f h• Limitations of the TEM
• Current research and future trend
• Resources
Lecture Two: The InstrumentLecture Two: The Instrument
• OpticsOptics
• ElementsEl t G– Electron Guns
– Lens
– Recording system
• TEM Modes/alignment