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ION BEAM ANALYSIS
L. C Feldman
New Trends in Ion Beam Research, Gramado Brazil, 14-16 Nov 2005
© David N. Jamieson 2005
keV electrons and MeV ions interact with matter
30 keV e− 60 keV e−
10 µm
2 MeV He+
5 µm
0.5 µm •Deep probe •Large damage at end of range
• Restricted to 10 µm depth, large straggling • Low beam damage
© David N. Jamieson 2005
Introduction • Ion Beam Analysis • The Nuclear Microprobe
– Accelerators: Brightness – Focusing MeV ion beams – Data Acquisition – Imaging modes
Part II: Nuclear microprobe applications photons ions
ions
x-rays
nuclear fragments
ions
electrons
electrons
holes
© David N. Jamieson 2005
ION BEAM ANALYSIS
L. C Feldman
New Trends in Ion Beam Research, Gramado Brazil, 14-16 Nov 2005
© David N. Jamieson 2005
REVIEW: Lecture of Sept 30 RBS
RBS= Rutherford Back-scattering Simplest conceptually and most accurate in terms of coverage (atoms/cm2) Depth resolution (in its simplest form) ~ 2-200 nm (Can measure surface coverage, cannot define depth well) Ideal thin film technique for stoichiometry, depth—does not reveal chemical nature/bonding Spatial resolution – typically 1mm--to– 1 micron
VARIATIONS ON THE (ION BEAM) THEME
Given an ion beam and the RBS knowledge there are a variety of specialized techniques: 1) Forward recoil scattering—hydrogen detection
2) Channeling—crystallographic information
3) Nuclear reaction analysis—light ion detection
4) PIXE-proton induced x-ray analysis
5) Medium energy ion scattering –high depth resolution (1nm) form of
RBS
Main features of RBS Elements: Be - U Standard Conditions : 2 MeV 4He beam Silicon detector: 10 minutes per sample Precision: Stoichiometry: < 1% relative Thickness: < 5% Sensitivity Bulk: 1 % to 10-4 , depending on Z Surface: 1 to 10-4 Monolayers Depth Resolution: 1 to 10 nm Data analysis : e.g. by RUMP software: http://www.genplot.com/ Remarks: Accessible depth range ~ 1mm No light elements detectable on heavy substrates
6. Elastic Recoil Detection Analysis & other
Incident Beam - 2 MeV He
ERDA detector
Sample
Filter
RBS detector
ERDA
Incident Beam
Axial STIM Detector
Sample
RBS detector Off axis STIM Detector
Scanning Transmission Ion Microscopy (STIM)
© David N. Jamieson 2005
Main features of ERDA Elements: H – U (Mainly applied for hydrogen) Standard Conditions: ~100 MeV heavy ion beam (2 MeV 4He beam for hydrogen detection) TOF, magnetic, gas ionisation detector, solid state detector 10 minutes per sample Precision Stoichiometry: 1% relative Thickness: < 5% Sensitivity Bulk: % to 10-5 , depending on Z Depth Resolution: 1 to 10 nm Remarks: Simultaneous profiles of all elements Accessible depth range: ~ 1um Light elements detectable on heavy substrates
Channeling
• Solids have crystal structure • Therefore the degree of scattering depends on
• angle • Phenomenon of “channeling” discovered in
1960’s.
0 degrees 11 degrees
(random)
45 degrees
© David N. Jamieson 2005
4. Particle Induced X-ray Emission (PIXE) 1: Knock out electron from K-shell (ionization) 2: Decay from L or M shell produces K x-rays
Discovered by G. Moseley in 1910
Ion velocity ≈ Electron orbital velocity
22
)1(43
2−== Z
akehE
o
ν
© David N. Jamieson 2005
Main features of PIXE Elements: C - U Standard Conditions: 3 MeV proton beam Si(Li), Ge detector 10 minutes per sample Precision Stoichiometry: 5% relative Generally used for trace element analysis Absolute concentrations: mainly by calibration standards Sensitivity: 1 to 100 ppm, depending on Z and matrix Depth Resolution: No depth information Remarks Probed depth is tens of um Often used with raster imaging (proton microprobe)
18O(p,α) 15N Ep=0.73MeV, Q=3.98MeV -------------------------------------------------------------------------------------------------------------------- 2H(3He, p)4He E3He=0.7MeV, Q=13.0Mev
II. Nuclear Resonance Profiling - the projectile penetrates the nucleus and induces a nuclear reaction; the reaction product is detected.
106
0
105
104
103
102
101
100
10-1
10-2
10-3
10-4
10-5
100 200 400300 500 600 700 800 900
95
151
216
334
629 73084618 15O(p, ) Nα
Seç
ão d
e ch
oque
dife
renc
ial (
b/sr
)µ
Energia (keV)
Resonant nuclear reactions
18O 15N p
α
106
0
105
104
103
102
101
100
10-1
10-2
10-3
10-4
10-5
100 200 400300 500 600 700 800 900
95
151
216
334
629 73084618 15O(p, ) Nα
Seç
ão d
e ch
oque
dife
renc
ial (
b/sr
)µ
Energia (keV)
Resonant nuclear reactions
pE E∼ r
mylar (13 m)µdetectorsemicondutor
amost ra
detector (BGO)
p,α
(a)
(b)raios γ
106
0
105
104
103
102
101
100
10-1
10-2
10-3
10-4
10-5
100 200 400300 500 600 700 800 900
95
151
216
334
629 73084618 15O(p, ) Nα
Seç
ão d
e ch
oque
dife
renc
ial (
b/sr
)µ
Energia (keV)
ER
ER
ER
E (> E )2 1
E1
Amostra
Resonant nuclear reactions
Examples
0 2 4 6 8 10 120
1
429 431 433Energia dos Prótons (keV)
15N(p,αγ)12C
Rend
imen
to (
u.a.
)
Profundidade (nm)
15N
(1019
.cm
-3)
0 2 4 6 8 10 120
429 431 433
15N(p,αγ)12C
Proton Energy (keV)
Rend
imen
to (
u.a.
)
Profundidade (nm)
15N
(1019
.cm
-3
15N profile As prepared Vac annealed
15N 15N
Nuclear resonance depth profiling of Al2O3 on Si(100)
(Baumvol et al., Porto Alegre)
Overlapping peaks in MEIS spectrum (M. Copel et al., IBM)
Main features of NRA Elements: H(D) - Al Standard Conditions :~ 1 MeV proton beam (15N, 19F, etc. for H-detection) NaI-, Ge-detector (Si detector for non-g reactions) 15 minutes per measurement 5 hours per profile Precision Composition: 5% relative Absolute concentrations : Only by calibration standards Sensitivity: ppm to % depending on element (ppb to ppt for CPA) Depth Resolution: 1 to 20 nm Probed depth ~ um
Examples of nuclear reactions suitable for NRA: 7Li(p,a)4He Ep » 3 MeV, s » 3 mb/sr, Q = 17.3 MeV 12C(d,p)13C Ed » 1-3 MeV, Q = 2.7 MeV 9Be(3He,p)11B EHe » 1-5 MeV, Q = 10.3 MeV 31P(a,p)34S Ea » 3 MeV, Q = 0.63 MeV 7Li(p,n)7Be Ep » 2 MeV 1H(15N,12C)ag EN = 6.4 MeV, resonance 19F(p,ag)16O Ep = 340, 484, 872 keV, resonances 27Al(p,g)28Si Ep = 991 keV, narrow resonance
Nanoscale Vanadium Oxide
R. Haglund, L.C. Feldman, R. Lopez, E. Donev, J. Suh
Vanadium oxide undergoes an amazing phase transition at roughly room temperature
Low temperature -semiconductor-high optical transmission, poor conductor
High temperature-metal-low optical transmission, excellent conductor
Properties of vanadium dioxide • Semiconductor to metal transition
► Tc ~ 68 oC in the bulk ► T < Tc semiconducting phase ► T > Tc metallic phase ► opt./elec. properties change
Animation by B. Muller http://exploration.vanderbilt.edu
Introduction Nanocrystals VO2 Arrays Percolation Approximation
DeNatale et al., J.A.P. 1989
High temperature phase Low temperature phase
122.6º
5.75 Å
5.38 Å
4.56 Å 4.55 Å
2.88 Å
4.55 Å
Tetragonal(P42/mnm) Monoclinic (P21/c)
Structural Phase Transition
Quantum dots are useful in biology because:
• Small size (=> image cellular components) • Incredibly bright (= enhanced sensitivity, early
detection) • Multiplexed detection (=> multiple simultaneous
signals) • Photostability (= dynamic imaging, sample archive) • Multivalent Surface (=> enhanced recognition
and targetting) All of these properties originate from the
nanometer size of the dots.
Dye vs. Nanocrystal Spectral Characteristics
Dye Molecules (Alexa)
Nanocrystals
500600
700
0.5
1.0
1.5
2.0
2.5
3.0
absorpt ion
0
9000
4 7 5 5 2 5 5 7 5 6 2 5 6 7 5
wavelenght (nm)
“Fundamentals of Surface and Thin Film Analysis,” L.C. Feldman and J.W. Mayer, North Holland-Elsevier, N.Y. (1986)
“Fundamentals of Surface and Thin Film Analysis,” L.C. Feldman and J.W. Mayer, North Holland-Elsevier, N.Y. (1986)
“Fundamentals of Surface and Thin Film Analysis,” L.C. Feldman and J.W. Mayer, North Holland-Elsevier, N.Y. (1986)
“Fundamentals of Surface and Thin Film Analysis,” L.C. Feldman and J.W. Mayer, North Holland-Elsevier, N.Y. (1986)
“Fundamentals of Surface and Thin Film Analysis,” L.C. Feldman and J.W. Mayer, North Holland-Elsevier, N.Y. (1986)
“Fundamentals of Surface and Thin Film Analysis,” L.C. Feldman and J.W. Mayer, North Holland-Elsevier, N.Y. (1986)
“Fundamentals of Surface and Thin Film Analysis,” L.C. Feldman and J.W. Mayer, North Holland-Elsevier, N.Y. (1986)
“Fundamentals of Surface and Thin Film Analysis,” L.C. Feldman and J.W. Mayer, North Holland-Elsevier, N.Y. (1986)
“Fundamentals of Surface and Thin Film Analysis,” L.C. Feldman and J.W. Mayer, North Holland-Elsevier, N.Y. (1986)
“Fundamentals of Surface and Thin Film Analysis,” L.C. Feldman and J.W. Mayer, North Holland-Elsevier, N.Y. (1986)
“Fundamentals of Surface and Thin Film Analysis,” L.C. Feldman and J.W. Mayer, North Holland-Elsevier, N.Y. (1986)
“Fundamentals of Surface and Thin Film Analysis,” L.C. Feldman and J.W. Mayer, North Holland-Elsevier, N.Y. (1986)
“Fundamentals of Surface and Thin Film Analysis,” L.C. Feldman and J.W. Mayer, North Holland-Elsevier, N.Y. (1986)
“Fundamentals of Surface and Thin Film Analysis,” L.C. Feldman and J.W. Mayer, North Holland-Elsevier, N.Y. (1986)
“Fundamentals of Surface and Thin Film Analysis,” L.C. Feldman and J.W. Mayer, North Holland-Elsevier, N.Y. (1986)
“Fundamentals of Surface and Thin Film Analysis,” L.C. Feldman and J.W. Mayer, North Holland-Elsevier, N.Y. (1986)
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