School of Ion Beam Analysis and Accelerator Applications N R A
Nuclear Reaction Analysis
Resonances
Gábor Battistig
Research Institute for Technical Physics
and
Materials Science
(MTA - MFA)
Budapest, Hungary
battisti@mfa.kfki.hu
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 1
School of Ion Beam Analysis and Accelerator Applications N R A
Inelastic nuclear collision with nuclear excitation
Nuclear reaction in general
A(a,b)B
Isotope specific!
Projectile energy must be higher than
Coulomb barrier
AA Aa Ab AB Z AZ ae2
1
Z A Z a Zb Z B Ec Z A Z a AA 3 [ MeV ]
R
Ea E A Eb EB Q
Q ( M a M A M b M B )c 2 M B Mb
Eth Q
Q 0 Exoterm M B Mb Ma
Q 0 Endoterm
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 2
School of Ion Beam Analysis and Accelerator Applications N R A
Ion-Gamma reaction : 19F(p,g)20Ne Q=12.845 MeV
Ion-Ion reaction : 19F(p,a)16O Q=8.115 MeV
Ion-Neutron reaction : 19F(p,n)19Ne Q=-4.020 MeV
Particle Induced Activation Analysis (PAA) : 19F(p,n)19Ne b 19F
Energy levels and
cross sections
in nuclear reactions
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 3
School of Ion Beam Analysis and Accelerator Applications N R A
Natural abundance of stable sotopes
1H - 99.985% 2H - 0.015%
3He - 0.0001% 4He - 99.999%
6Li - 7.56% 7Li - 92.44%
9Be - 100%
10B - 19.8% 11B - 80.2%
12C - 98.89% 13C - 1.11%
14N - 99.64% 15N - 0.36%
16O - 99.76% 17O - 0.04% 18O - 0.20%
19F - 100%
23Na - 100%
24Mg - 78.99% 25Mg - 10.0 % 26Mg - 11.01%
27Al - 100%
28Si - 92.23% 29Si - 4.67% 30Si - 3.10%
31P – 100%
50Cr – 4.35% 52Cr – 83.79% 53Cr – 9.5% 54Cr – 2.36%
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 4
School of Ion Beam Analysis and Accelerator Applications N R A
Most used particle induced nuclear reactions of light elements
Proton induced Deuteron induced 3He induced 4He induced
reactions Q [MeV] reactions Q [MeV] reactions Q [MeV] reactions Q [MeV]
6Li(p,a)3He 4.02 2H(d,p)3He 4.03 2H(3He,p)4He 18.35 10B(a,p)13C 4.06
7Li(p,a)4He 17.35 3He(d,a)1H 18.35 6Li(3He,p)8Be 6.79 11B(a,p)14C 0.78
9Be(p,a)6Li 2.13 12C(d,p)13C 2.72 9Be (3He,p)11B 0.32 14N(a,p)17O -1.19
10B(p,a)7Be 1.15 13C(d,p)14C 5.95 9Be(3He,a)8Be 18.91 19F(a,p)22Ne 1.67
11B(p,a)8Be 8.58 14N(d,p)15N 8.61 12C(3He,p)14N 4.78 31P(a,p)34S 0.63
15N(p,ag)12C 4.97 14N(d,a)12C 13.57 12C(3He,a)11C 1.86
18O(p,ag)15N 3.98 16O(d,p)17O 1.92 18O(3He,p)20F 6.87
19F(p,ag)16O 8.11 16O(d,a)14N 3.11 18O(3He,d)19F 2.50
23Na(p,ag)24Mg 11.69 19F(d,a)17O 10.03 18O(3He,a)19O 12.51
27Al(p,g)28Si 11.59
29Si(p,ag)30P 5.59
52Cr(p,ag)53Mn 7.56
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 5
School of Ion Beam Analysis and Accelerator Applications N R A
Principle 100
12 C(d,p )13 C
80 0
s(mb sr-1)
150°lab
4He+, 3He+, 2H+, 1H+, etc
60
Q=2.77 MeV
Sample 40
Absorber
20
foil
0
Detector
0 200 400 600 800 1000 1200
16O(d,p )17O Energie (keV)
1
14
16O(d,p )17O
0 12
16O(d,p )17O
10 1
12C(d,p )13O
s (mb sr -1)
0 8 150°lab
Q=1.05 MeV
Counts
6
4
2
0
Energy 0 200 400 600 800 1000 1200
Energie (keV)
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 6
School of Ion Beam Analysis and Accelerator Applications N R A
Experimental setup
Vacuum chamber Vacuum chamber
LN2 Surface barrier LN2 Sample
trap detector trap
Filter foil
Ion Ion
beam beam g detector
Sample
Anular surface Filter foil
barrier
detector
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 7
School of Ion Beam Analysis and Accelerator Applications N R A
Experimental results
600 nm SiO2 layer; 900 keV, Deuteron beam
Yield:
Nb
NA
ds ( )
N a
d
Well known reference sample is needed for quantification !!!
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 8
School of Ion Beam Analysis and Accelerator Applications N R A
Experimental results
170 nm AlxN layer, 1.7 MeV d beam
Many reactions, many, sometimes overlapping peaks.
Total amount of the given isotope can be determined.
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 9
School of Ion Beam Analysis and Accelerator Applications N R A
Thin sample : interferences
900 keV 2H+ on TiOxNy film
Numerous overlapping peaks from 250 0
14N(d,p
0-7) and
14N(d,a ) reactions.
0,1
200 0
150 0
16
O referenc e
Count s
16 14
film containing O and N
100 0
Reaction Q-values are known
50 0
In principle, interferences can be
accounted for.
In practice we avoid having to. 0
10 0 200 300 40 0
C hannels
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 10
School of Ion Beam Analysis and Accelerator Applications N R A
Reference samples
YU Anodic isotopic Ta2O5 thin films for 16O and 18O
NU NR Certified 16O and 18O films available from different
YR sources.
For thin targets, the cross section ratios of 12C(d,p)13C, D(3He,p)4He, 14N(d,a)12C,
14N(d,p)15N, 15N(d,a )13C and 15N(p,a )12C to that of 16O(d,p )17O have been obtained by
0 0 1
using stoichiometric frozen gas targets of CO2, NO and D2O.
This enables the reliable and robust Ta2O5 reference targets to be used as a
reference for NRA determinations of D, 12C, 14N and 15N.
Davies, J. A., T. E. Jackman, et al. (1983). "Absolute calibration of 14N(d,a) and 14N(d,p)
reactions for surface adsorption studies." Nucl. Instr. and Meth. 218: 141-146.
Sawicki, J. A., J. A. Davies, et al. (1986). "Absolute cross sections of the 15N(d,a0)13C and
15N(p, a )12C reaction cross sections." Nucl. Instr. and Meth. B15: 530-534.
0
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 11
School of Ion Beam Analysis and Accelerator Applications N R A
Depth Profiling : Principle
• A channel of width dEc at energy Ec in
the spectrum corresponds to a slice
dx
x of width dx at depth x in the sample,
with Ec and dEc being inversely
E inc related to x and dx through a linear
q combination of the stopping powers
C(x) for the incident and outgoing particle
• The number of particles accumulated
s (x) into that histogram bin is proportional
to C(x), dx, and s(Ex), where Ex is the
energy of the incident beam when it
gets to depth x;
Y Ns ( E )
E
Area A
dE
Cxs ( E )
C ( x)s ( E )dx
x
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 12
School of Ion Beam Analysis and Accelerator Applications N R A
Cross section
Depth profiling 1.5
ds /d (mb. sr-1)
1.0
Depth profiling nitrogen 0.5
in titanium via 0.0
600 800 1000 1200 1400
14N(d,a )12C
1 Energy (keV)
Spectra Concentration profile
b) d)
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 13
School of Ion Beam Analysis and Accelerator Applications N R A
Ion implantation of SiC
RBS + channeling = lattice disorder
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 14
School of Ion Beam Analysis and Accelerator Applications N R A
RBS + NRA = More information
W. Jiang et al. / Nucl. Instr. and Meth. in Phys. Res. B 161±163 (2000) 501
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 15
School of Ion Beam Analysis and Accelerator Applications N R A
Thin sample : summary
dE/dx not needed
Shape of s(E,q) much more important than absolute value.
Precision standards are used rather than precision cross
sections (Standardless NRA?)
Approximate relative cross sections are needed to help in
experimental design (isotopes …)
Reaction Q values are needed - these are easily accessible
and well known.
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 16
School of Ion Beam Analysis and Accelerator Applications N R A
Resonances
18O(p,a)15N cross section
6
Cross section in
Differential Hatáskeresztmetszet [µb/sr]
10
10
5 the resonance:
Differenciális cross section [mb/sr]
10
4
152 keV 334 keV
Breit-Wigner (Lorenz)
3
function
10 216 keV 629 keV
2
s R (E) K
2
10
2
( E ER ) 2
1
10
0
18
O(p,a) N
15 4
10
-1
10 Q = 3.9804 MeV
-2
10
= 135°
-3
10
-4
10
-5
10
100 200 300 400 500 600 700 800 900
Proton Energy [keV]
Proton Energia [keV]
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 17
School of Ion Beam Analysis and Accelerator Applications N R A
Most used Narrow Resonances in Depth Profiling
Reaction Resonance energy Resonance width
18O(p,a)15N 152 keV 100 eV
29Si(p,g)30P 413.9 keV
15N(p,a)12C 429 keV 120 eV
30Si(p,g)31P 620.4 keV 68 eV
18O(p,a)15N 629 keV 2000 eV
27Al(p,g)28Si 632.23 keV 6.7 eV
23Na(p,g)24Mg 676.7 keV „straggling” of C(x)
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 21
School of Ion Beam Analysis and Accelerator Applications N R A
Excitation curve
G(E) beam - Gaussian,
+ Doppler energy spread due to the thermal vibration of the target atoms
2MAE
s D (E )
2
kT
Ma
(E) rersonance lineshape - Lorantzian
2
s R (E ) K
2
(E E R ) 2
4
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 22
School of Ion Beam Analysis and Accelerator Applications N R A
T(E) beam energy straggling
f(u)
E
Energy loss u
2
The charged particles lose their 0.2 mg/cm
keV protons in CH
152 152 keV-os protonok 2
energy in independent collisions stragglingje CH2-ben
with electrons. 2
0.3 mg/cm
Tetszoleges egység
2
0.4 mg/cm
2
0.6 mg/cm
f(u;x) tends towards a Gaussian 0.8 mg/cm
2
"
for large x 1 mg/cm
2
2Z
s (f (u )) S x
A
0.0 0.5 1.0 1.5 2.0
Energy loss [keV]
Energia veszteség [keV]
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 23
School of Ion Beam Analysis and Accelerator Applications N R A
„Straggling” S ‘ straggling ’ of C(x)
On average, m energy-loss events per
unit length
* * * *
f(u) f(u) f(u) f(u)
For thickness x mx events on average
f(u)*f(u) g(u;x)
0 u
n
g u ; x Pn (mx )f *n (u )
n 0
(mx )n
Pn mx e mx
n!
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 24
School of Ion Beam Analysis and Accelerator Applications N R A
Experimental excitation curves
Si18O2 /Si sample,
thermally grown, 20 mC /point
Beam energy spred + Doppler
broadening: 100 eV
Resonance width: 100 eV
Ta218O5 /Ta sample, anodically
oxidised, 20 mC /point
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 25
School of Ion Beam Analysis and Accelerator Applications N R A
Tilting the sample – increases the
virtual thickness of the layer
1
x ' x
cos
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 26
School of Ion Beam Analysis and Accelerator Applications N R A
Depth resolution
0.5
10 A
+ 0.4 20 A
Narrow resonance width 30 A
0.3
Large dE/dx (~ 100 keV)
40 A
Beütés
Yield
„negligible cross section outside 0.2
the resonance – Background-free SiO 2
- 0.1 x
Straggling – beam broadens by
0.0
depth 152 153
Multiple Scattering at tilted Proton Energia [keV]
Proton Energy [keV]
sample
Depth resolution
vs Depth
: tilt angle
line: straggling
circles: MS
crosses: overall
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 27
School of Ion Beam Analysis and Accelerator Applications N R A
Depth Profiling by Resonance - Summary
As for thin samples, plus need for accurate S(E)
low energy – large stopping – high depth resolution
Stronger requirement for shape accurate s(E,q) for accurate depth
profiling
Straggling and Multiple scattering gradually decreases resolution
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 28
School of Ion Beam Analysis and Accelerator Applications N R A
Typical experimental results
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 29
School of Ion Beam Analysis and Accelerator Applications N R A
Isotopic tracing study of the microscopic mechanisms of oxygen
transport in the oxide growing during dry oxidation of silicon.
18O depth profile
SiO2 Silicon
16 O
2
then
18
88 O2
88
88
8
exchange
exchange growth
800
18O depth profile
Experimental
600
excitation curve 400
200
0
150 155 160 165 170 175 180
Energy [keV]
Interpretation of the spectra in terms of 18O depth profile, demonstrating
surface exchange and that the growth takes place at the SiO2/Si interface
through interstitial oxygen movement: direct confirmation of the Deal and Grove
model for growth x > 10 nm.
No isotopic exchange in the matrix (natural abundance, 0.2%) except near the surface.
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 30
School of Ion Beam Analysis and Accelerator Applications N R A
18O depth profile
Coups (u.a)
Yield
150 160 170 180 190 200 210
Energy [keV]
Energie (keV)
Sequential oxidations in 100 mb 16O2 (40 h) at 1100°C, yielding 1600 Å Si16O2 then in 18O2 (5
h, 10 h and 24 h: additional 100, 285 and 405 Å). Excitation curve registration with target
tilted to 60°. I. Trimaille et al. GPS, Paris
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 31
School of Ion Beam Analysis and Accelerator Applications N R A
Isotopic tracing by sequential oxydation of SiC
16O (40 h) then 18O (5 h, 10 h and 24 h)
2 2
6H-SiC
6H-SiC
C terminated 1,0
Si terminated surface
surface 0,8
C u sYield
0,6
[ O](%)
Yield
C u s(u )
o p .a
o p (u )
.a
0,4
18
0,2
0,0
0 100 200 300
Thickness [Å]
Epaisseur (Å)
150 152 154 156 158 160 162 164 5 5 6 6 7 7 8 8
10 15 10 15 10 15 10 15
Energy [keV]
Energie(keV) E e ie[keV]
Energy (ke )
n rg V
Sequential 16O2/18O2 oxidations, same conditions as for Si. SiC is a polar crystal: silica grows
on both faces, similarly to the Si case, but the Si and C faces produce slow and fast growth.
Isotopic tracing measurements of this type allow one to investigate with great sensitivity the
near surface and interface properties of the silica produced by oxidation of SiC.
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 32
School of Ion Beam Analysis and Accelerator Applications N R A
Hydrogen profiling with a nuclear resonance
Hydrogen implantation
1H(15N,ag)12C profile in silicon
(1016 cm-2, 40 keV)
from W.A. Lanford, NIMB66(1992),68
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 33
School of Ion Beam Analysis and Accelerator Applications N R A
Study of thin hafnium oxides deposited by atomic layer deposition
J.-J. Ganem, NIM B 219–220 (2004) 856
Excitation curves measured using the 151 keV 18O(p;ac)15N resonance on 3.5 nm (a) and 7.5 nm (b) HfO2
samples oxidized in 18O2 atmosphere at 425 C just after: deposition (black circles), post-deposition N2
anneal at 425 C (open circles) and post-deposition N2 anneal at 800 C (open squares).
After deposition the films present chlorine contamination and a lack of oxygen. They are unstable toward
thermal oxidation since a high oxygen transport and exchange mechanisms occur during the process.
Oxygen diffusion can be significantly reduced after a thermal anneal in N2 atmosphere.
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 34
School of Ion Beam Analysis and Accelerator Applications N R A
Ultrathin silicon oxynitride film formation
Experimental excitation curves of the 18O(p,a)15N reaction for samples with (a) deferent 15N areal
densities, sequentially oxidized in 16O2 (60 min) and in 18O2 (90 min). The arrows indicate the
energy position of the surface (dashed) and of the SiO2/Si interface (solid) in each sample; (b) no
N prior to oxidation, oxidized under the same conditions as samples in (a).
(i) N amounts as low as 1/30 of a monolayer at the surface of Si wafers hamper the oxidation of
Si, and the higher the N concentration, the thinner the oxynitride films;
(ii) (ii) during the film growth, N and O are responsible for the atomic transport, while Si remains
immobile;
(iii) N, which is initially present at the surface of the Si wafer, migrates during oxidation, remaining
at the near-surface and at the near-interface regions of the film.
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 35
School of Ion Beam Analysis and Accelerator Applications N R A
Silicon isotopic tracing with the 29Si(p,c) narrow resonance near
415 keV
c)30P excitation curves from an enriched silicon single crystal before and after
29Si(p,
thermal oxidation, showing loss of silicon during the oxidation process.
I.C. Vickridge et al, NIM B 161±163 (2000) 441
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 36
School of Ion Beam Analysis and Accelerator Applications N R A
Annealing of ZrAlxOy Ultrathin Films on Si in a Vacuum or in O2
E. B. O. da Rosa et al., Journal of The Electrochemical Society, 148 G695-G703 (2001)
ZrAlxOy films were deposited at a rate of 0.3 nm/min by reactive sputtering using a Zr80-Al20 atomic
composition target in an oxygen-containing plasma directly on Si(001) substrates. Postdeposition
annealings were performed ex situ at 600°C for 10 min, either in high vacuum (p10-5 Pa) or in 710-3
Pa of dry 98.5% 18O2.
Areal densities of Al and Si were estimated from the areas of the excitation curves of the
27Al(p,g)28Si and 29Si(p,g)30P nuclear reactions around the resonance energies at 404.9 and 414 keV.
The as-deposited film has an approximate composition Zr4AlO9.
Normalized excitation curves of the
18O(p,a)15N nuclear reaction around the
resonance at 151 keV before and after
thermal annealings and the used
experimental geometry.(b) Normalized 18O
concentration vs. normalized depth for
the as deposited and 18O2-annealed
samples.
Solid lines represent the as-deposited sample, empty
circles and triangles correspond to vacuum and 18O-
annealed samples, respectively.
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 37
School of Ion Beam Analysis and Accelerator Applications N R A
(a) Excitation curves of the 27Al(p,g)28Si nuclear reaction around the resonance at 404.9
keV before and after thermal annealings and the used experimental geometry.
(b) Normalized 27Al concentration vs. normalized depth for the as-deposited and vacuum-
annealed samples.
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 38
School of Ion Beam Analysis and Accelerator Applications N R A
(a) Excitation curves of the 29Si(p,g)30P nuclear reaction around the resonance at 414 keV
before and after thermal annealings.
(b) Normalized 29Si concentration vs. normalized depth for the as-deposited, 18O2- and vacuum-
annealed samples.
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 39
School of Ion Beam Analysis and Accelerator Applications N R A
Summary
• Isotope specific – unique tool for studying transport processes
• Absolute concentration by well-known reference samples (no
need of exact knowledge of cross section)
• Narrow resonances: almost atomic depth resolution at the
surface
13-24 March, 2006, ICTP, Trieste, Italy G. Battistig, MTA – MFA Budapest, Hungary 40