henri i. boudinov instituto de física, universidade federal do rio grande do sul
DESCRIPTION
Ion Beam Analysis Part 1. Henri I. Boudinov Instituto de Física, Universidade Federal do Rio Grande do Sul Porto Alegre, RS, Brazil [email protected] 26_10_2009NanoSYD, MCI, SDU, Sønderborg , Denmark. Outline. The Porto Alegre Ion Beam Centre Interaction of ions with matter - PowerPoint PPT PresentationTRANSCRIPT
Henri I. BoudinovInstituto de Física, Universidade Federal do Rio Grande do Sul
Porto Alegre, RS, Brazil
26_10_2009 NanoSYD, MCI, SDU, Sønderborg , Denmark
Ion Beam AnalysisPart 1
• The Porto Alegre Ion Beam Centre• Interaction of ions with matter• Stopping power• Rutherford Backskattering Spectrometry (RBS)• Channeling• Compositional and defect depth profiles• Proton Induced X-ray emission (PIXE)• Nuclear Reaction Analysis (NRA)• Microbeam analysis
Outline
Porto Alegre Ion Beam Centreestablished in 1981• Controllable Materials Modification
• Facilities• 0.2-3MV Tandetron• 30-500kV Single Ended Implanter• 10-250kV Medium Current Implanter• Implantation 10keV ~15MeV (up to 1mA)• Sample size up to 10cmx10cm• Hot (800oC) or cold (~LN)
• Applications• Ion Beam Synthesis
• Buried and surface oxides and silicides• Nanocristals
• Ion Implantation• Defect Engineering• Proton beam lithography
• potentially 1m resolution to 10m depths
• Advanced Materials Analysis• Facilities
• 3MV Tandem• Techniques include RBS, MEIS, ERDA, PIXE,
NRA• Channelling Spectroscopy for damage
analysis• Fully automated collection and analysis• Micro-beam with full scanning• External Beam for vacuum sensitive samples
• Applications• Thin Film Depth Profiling• Compositional Analysis• Disorder Profiling of Crystals• 3-D elemental composition and mapping
Porto Alegre Ion Beam Centre
• Ion Beam Modification of Materials
• Ion Beam Analyses
• Basic Physics
Ion Beam for:
• Material Science• Solid State Physics• Atomic and Molecular Physics
• Charged Particles• Electrons: e-, e+, b-, b+ 10m• Ions: p+, He++ (a), etc.. 1m
• Uncharged Particles• X-rays and g-rays 10cm• neutrons 10cm
Penetration of the Radiations in Solids
Ion Implanter
3MV Tandetron accelerator
E. Rutherford, 1911N.Bohr, 1913-54, 1948E. Fermi, 1924-H.A. Bethe, 1930-F. Bloch, 1933-L. Landau, 1944-
....
Penetration of charged particles through matter
Experimental ingredients
Ions : Z1=-1,1,2,...~100, electrons, muons, clusters,...
energies ~1eV – 1011 eV
Target : Z2 = 1,2,.. ~100, solids, gases, liquids, plasma,...
Bohr, Bethe,...
Stopping Power
dE/dx = N.SdE/dx – energy loss [eV/nm]
N – atomic density [nm-3]
S – stopping power [eV.nm2]
dE/dx : two types
vion << ve : the electrons shield (passive)
Elastic Collisions
Low energies
The ion lose energy to move the target atoms
Nuclear Stopping Power
Classic
vion ~ ve : active electrons (ionization/excitation, plasmons,...)
Inelastic Collisions
High energies
The ion lose energy to the electrons of the target
Electronic Stopping Power
Quantum
Electronic Energy loss (high energies)
Classical theory
dE/dx ~Z12 ln (|Z1|)
for Z1/v >> 1
Quantum theory
dE/dx ~Z12
First-order : for Z1/v <<1
Results from
Coupled-Channel Calculations
proton (b=1) on H(1s)
Results from
Coupled-Channel Calculations
anti-proton (b=1) on H(1s)
Transition from electronic to nuclear stopping power
Penetration of Ions in Silicon
10-3 10-2 10-1 100 101 102 103 104 10510-3
10-2
10-1
100
101
(dE/dx)e
(dE/dx)n
E3
E2E1
dE/d
x (e
V/io
n/A)
E(keV)
Target Si
ion mass E1 E2 E3 He 4 0,5 keV 2 keV 0,5 MeV B 11 3 keV 17 keV 3 MeV As 75 73 keV 800 keV 200 MeV Bi 209 530 keV 6000 keV 2000 MeV
• Energy Loss
The Stopping and Range of Ions in Matter
Software SRIM
Materials Radiation Analysis Concept
• AES (electron in and out)• RBS, MEIS, LEIS, ISS (ion in and out)• XRF (X-ray, in and out)
• XPS (X-ray in, electron out)• SEM/EDS (electron in, X-ray out)• SIMS and ERDA(ion in, target out)• PIXE (ion in, X-Ray out)
• PIGE, NRA, ...
STIMMeasure the energy
loss of transmitted ions to map density
variations
PIGENuclear reactions give characteristic gamma rays from light nuclei (e.g. Li, B, F)
RBSEnergy of recoiling protons give element composition and elemental depth profiles
Ion Beam Analysis (IBA)
PIXECharacteristic X-ray emissionSimultaneous part-per-million detection of trace elements from Na to U
Sample
1 – 3 MeV proton beam
Rutherford BackScattering
• Energy of ions recoiling from nuclear collisions depends on mass and depth
• Measure light elements (C,N,O) and thickness or depth profiles
• MDL around 0.1%, but can be used to help quantify PIXE
Sample
Incident Ion
To detector
C
ONa
Cl
RBSSpectrum of 2m diameter marine aerosol particle showing sodium and chlorine and carbon and oxygen from the plastic support film
Backscattering Spectrometry
Yield • Concentration
Energy • Element (K)• Depth (dE/dx)
E1
E0
K = E1 /E0
x
KE
E
E1
E0
2
1
E = E0 – dE/dx(in) x / cos 1
E1 = K E - dE/dx(out) x / cos 2
K E0 - E1x =K dE/dx(in) / cos 1 + dE/dx(out) / cos 2
RBS profiling
Fluctuations
Dx
1
2
3
i. number of collisions
ii. impact parameter
iii. charge state
iv. ...
i. roughness
ii. detector parameters
iii. beam spot
iv. ....
Phys
ics
Multiple scattering
Detector aceptance
Energy straggling
Beam spot
0 2 4 6 8 100
2
4
6
8
10
E1 KE0
Cou
nts
Energy0 2 4 6 8 10
0
2
4
6
8
10
E1 KE0
Cou
nts
Energy0 2 4 6 8 10
0
2
4
6
8
10
E1 KE0
Cou
nts
Energy0 2 4 6 8 10
0
2
4
6
8
10
E1 KE0
Cou
nts
Energy
monocrystal
Thin Film Analysis1. Structural information (near surface region)
2. Increased sensitivity to light impurities
Surface Peak
240 260 280 300 3200
5000
10000
15000
20000
random channeling <100>
He+(1.2 MeV) SIMOX
Cou
nts
Channel55 60 65 70 75 80 85 90
0
100
200
300
400
500
600
H+ (100keV) + SIMOX
High resolution
Cou
nts
keV
RBS MEIS
MEIS
0.0
0.5
1.0
1.5
2.0
2.5
75 80 85 90 95 1000.0
0.5
1.0
1.5
2.0
2.5
O
Si
As
RTA 1000ºC/10s
SIMOX Si
Cou
nts
FA 950ºC/15min
SIMOX Si
Energy (keV)Si peaks: • SIMOX better than Si• RTA better than FA
As+ 20keV, 5E14 cm-2 + annealing:
RTA 1000C/10s or FA 950C/15min
• Nondestructive and multielemental analysis technique • Elemental composition (stoichiometry) without a standard (1-5%
accuracy). • Elemental depth profiles with a depth resolution of 5 - 50
nanometers and a maximum depth of 2 - 20 microns. • Surface impurities and impurity distribution in depth (sensitivity
up to sub-ppm range). • Elemental areal density and thus thickness (or density) of thin
films if the film density (or thickness) is known. • Diffusion depth profiles between interfaces up to a few microns
below the surface. • Channeling-RBS is used to determine lattice location of impurities
and defect distribution depth profile in single crystalline samples
Rutherford backscattering spectrometry (RBS)
Elastic Recoil Detection Analysis
Characteristic X-rayphoton
Ejected electron
PIXE
Proton Induced X-ray Emission
• Analogous to EDS using MeV protons
• No primary bremsstrahlung, so low detection limits (1-10ppm)
• Can be made quantitative
FeCu Zn
K
Ca
Beam
Target(Ca)
Detector
Electronics
Counts
EnergyKa Kb
PIXE
0 2 4 6 8 10 12 14 161
10
100
1000
10000
100000
1000000
Sr
RbKb
RbKa
PbLb
ZnKbPbLa
ZnKaCu
Ni
FeKb
FeKa
Mn
Cr
TiKb
TiKa
CaKb
CaKaK
S
Si
Al
Mg
Na
Cou
nts/C
Energy (keV)
Buffalo River Sediment (NIST 8704)
Applications Microelectronics Environmental sciences Food processing Biological tissues Biotechnology Archaeology - Art Earth Sciences
Proton Induced Gamma Ray Emission
• MeV protons can tunnel through the Coulomb barrier of light nuclei to induce gamma emitting nuclear reactions
• Gamma energy is characteristic of specific isotopes
• Detection limits ~ 0.1 %• Useful for specific problems (e.g. F19,
B10/B11)
p F19
a
O16
IntermediateNe20 nucleus in
excited state
Decays to O16 + alphaparticle and emits
characteristic gamma raysg
Ne20
F19(p,ag)O16
^0
^1
^2
^3
100 300 500 700 900 1100 1300 1500 1700
f:\pc_users\jpn\971118\490001g4._ : Tourmaline std: GRR573
F F
B10 Al AlLi
Na
Tourmaline standard GRR573
PIGE
ERE ER
Nuclear Reaction Analysis (NRA)
p + 18O 15N + 4He
Nuclear Microscopy
LensBeam fromAccelerator
Scanningsystem
Map arrayY
X
Sample
Detectors
Image incomputermemory
• All types of data can be collected simultaneously
STIM
Scanning Transmission Ion Microscopy
• Energy loss of transmitted ions depends on thickness and density.
• Use energy loss mapping to image the structure of thin samples (up to 30m).
• (No chemical information)
EnergyHigh
Low
STIM image of the leg and claw of a wasp showing internal detail