1
Medium energy ion scattering and elastic recoil detection analysis for processes in
thin films and monolayers
Lyudmila V. Goncharova, Sergey Dedyulin, Mitch Brocklebank
Department of Physics and Astronomy, Western University ,
London, Ontario, Canada
Collaborators: P. J. Simpson (UWO), J. Botton (McMaster U.), D. Londheer (NRC)
Duoplasmatron Source
Sputter Source
Injector MagnetTandetron Accelerator
High Energy Magnet
RBS Chamber
ERD Chamber
MEIS Chamber
Implant Chamber
Group III,V Molecular BeamEpitaxy System
Group IV Molecular BeamEpitaxy System
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1.7 MeV Tandetron Accelerator Facility at UWO
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2D MEIS Data
2
21
122
122 cossin
MM
MMMEE od
•mass (isotope) specific•quantitative (2% accuracy)•depth sensitive (at the sub-nm scale)
Energy distributions:
77 84 910
500
1000
1500
O(buried)
Zr(buried)
O(surf)
Ge(buried)Si
(surf)
Yie
ld
Energy [keV]
SiO2/ Si /ZrO
2/GeO
x/Ge(001)
Experiment Total Spc
100keV H+, SiO2/poly-Si/ZrO2/Ge(100)
H+ E
nerg
y [k
eV]
Angle 115 120 125 130 135 140
H+ Y
ield
Angle [degree]
Energy distribution for one angle
Angular distribution for one element
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Outline
• Motivation
• Medium Energy Ion Scattering (MEIS) - Nucleation and growth in Si and Ge quantum systems
• Medium Energy Elastic Recoil Detection (ME-ERD) - H-terminated Si(001)
- H in HfSiOx ultra-thin films /Si(001)
• Conclusions and future directions
For the Age of Photonics…
• Continued developments in – miniaturization, – speed and complexity
• Wiring bottleneck• Need to merge electronics and photonics• III-V compounds dominate optoelectronics• Hybrid technologies are being used• OEICs and OICs incorporating Si/Ge detectors,
modulators and waveguides now functional
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D.J. Paul, Semicond. Sci. Tech. 19, R75 (2009)
Overcoming the indirect band gap
• Alloying Ge with Si and/or C• Stress• Brillouin zone folding
• Rare earth and transition metal impurity centres
• Quantum confinement– Wells (1-D)– Wires (2-D)– Dots (3-D)
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Band gap engineering
Experimental Approach
Ion beam implantation
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Tx, N2
*Stopping and Range of Ions in Matter, www.srim.org/
SRIM*
Photoluminescence (PL)h
h2
Life-time decay
X-ray Photoemission Spec.
Rutherford Backscat. (RBS)Elastic Recoil Detection (ERDA)Raman
Rutherford Backscat. (RBS)Elastic Recoil Detection (ERDA)Raman
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Growth and Analysis of Si QD• RT Implantation Si- or Ge+ 90keV 5x1016 -1x1017ions/cm2
• 120min @11000C (Si) or 9000C (Ge)
in furnace, 60 min @5000C in N2/H2 gas
• Early stage of formation governed
by diffusion
• Eventually Ostwald ripening
)(4 solSiSi CCrNDt
C
Link between defects in the SiO2 and formation of Si-QDs*
Ge QDPhotoluminescense in Ge quantum systems
• Ge QD PL has two components:
blue-green PL at ~2 eV (590 nm) independent of NC size
near infrared PL size dependent, compatible with a QC effect• Larger exciton radius (24 nm) compared with Si (~4nm) causes
larger confinement effect in Ge QD• Very challenging to fabricate a defect-free stable Ge QD!!!
N.L. Rowell, et al., JES 156, H913 (2009)
Ion beam implantation
Tx, N2
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Ge in Al2O3(0001): crystallization and ordering
E.G. Barbagiovanni, et al., NIMB 272 (2012) 74–77
XPS
• Shift of Ge peak towards the surface (RBS)
• GeOx peaks in XPS Ge loss via GeO desorption
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Ar sputtering prior to XPS analysis: Ge layer is 3-5nm deep
Al2O3(0001)
GexO
disordered Al2O3
Tx>1100oC
N2 Al2O3(0001)
Ge-QD
Cross-sectional TEM micrographs
• Contrast arising from stress fields and end of range implantation damage
• Moiré fringes become visible from the overlap of the crystal planes of Ge QD and the sapphire matrix
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Ge QD in Al2O3(0001): MEIS vs HRTEM
• Slow diffusion rate of the alumina matrix atoms at < Tmelt
• Ge blocking minimum can be related to the stereographic projection of the sapphire crystal and corresponds to the [111] scattering plane:
(1104) Al2O3 // (111)Ge and [211] Al2O3 // [112] Ge
100 105 110 115 120 1250.0
0.7
1.4
2.1
In
tegr
ated
Yie
ld
Scattering Angle [degrees]
Ge
Al
[111]
I.D. Sharp, Q. Xu, D.O.Y, et al., JAP 100 (2006) 114317
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Outline
• Motivation
• Medium Energy Ion Scattering (MEIS) - Nucleation and growth in SI and Ge quantum systems
• Medium Energy Elastic Recoil Detection (ME-ERD) - H-terminated Si(001)
- H in HfSiOx ultra-thin films /Si(001)
• Conclusions and future directions
Quantification in MEIS
• Scattering potential• Cross section• Neutralization
RBS vs MEIS
Normalized ion yield:
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Missing element from the picture… hydrogen!
Heavy Elements by MEIS or RBS
Light Elements by Elastic Recoil Detection
Detector
Light elements (He+ or H+)
Detector
He+
H+, He+ “Classical” ERDIncident energy = 1.6MeV He+
Incident angle = 75o
Recoil Angle = 30o
Al-mylar (range foil)
200 250 300 350 400 450 500 550 6000
50
100
150
200
Yie
ld
Energy [keV]
Kapton 1034 1051 1085 1091 1097
~150nm SiONH/Si(001)
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TEA detector for negative ions
Crucial points for detecting H ion recoils directly are:
• To increase the recoil cross-section
• To reduce (to suppress) the background originating mainly from elastically scattered incident ions
• To reduce recoil energy
V-
V+
MEIS
V-V+
ME-ERD
Only charged particles are detected by TEA
use incident beam ions without negative ion fractions and detect negative H- recoils
X+ H+,H, H-
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Selection of Incident Ions
• Potential candidates: B, N, Ne, Na, Mg, Al, Si, P…
• Limitations:
- possibility to produce these ions beam
- high beam current
- only H- are detected (fraction can
be small)
W.N. Lennard, et al. NIMB 179 (1981) 413
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0 200 400 600 8000
100
200
300
400
500
Incident beam: 500 keV Si
TEA center: 75
Yie
ld
Channel (Angle)
H-Si(001) fitting area background fit
ME-ERD for H-Si(001)
Incident beam: 500keV Si+
Incident angle = 45o
Recoil Angle = 75o (TEA centre)
Dose = 0.5CSi+
H-
60 70 80 900
5
10
15
20
Re
coil
En
erg
y [k
eV
]
Detector Angle [deg]
SiH
60 65 70 75 80 85 900
500
1000
1500
2000
2500
3000
Nor
mal
ized
Yie
ld
Detector Angle [deg]
Recoil E (3.0 keV) Recoil E (4.0 keV) Recoil E (5.0 keV)
H
Si
Although the fraction of Si- ions is small, it is not negligible!
60 70 80 900
5
10
15
20
R
ecoi
l Ene
rgy
[keV
]
Detector Angle [deg]
SiH
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ME-ERD for H-Si(001)
65 70 75 80 850
80
160
H-Si(001) 3keV H-Si(001) 4keV
Yie
ld
Detector Angle [deg]
H- Si(001) vs H-Si(111)
H- Si(001): assuming dihydride model 1.38x1015 /cm2
Sensitivity to H: 8x1013 H/cm2
H- Yield as a function of Si+ dose
• Irradiated area need to be refreshed!
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0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.00
100
200
300
400
500
600
700
800
500keV Si+ H-Si(001)E(H)= 4keV
Experimental Fit
Rec
oile
d H
- Y
ield
[cou
nts/
0.1 C
]
Si+ Dose [I, C]
YH(I) =984 exp (-I/k)
k=0.27 C
Without shifting irradiation area
• YH(I=0) = 984 ~ 30% of H is lost after 0.1C• Data shown below is without correction of H loss from
the surface
Si+
H-
60 70 80 900
5
10
15
20
R
ecoi
l Ene
rgy
[keV
]
Detector Angle [deg]
SiH
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ME-ERD for H-Si(001)
65 70 75 80 850
80
160
H-Si(001) 3keV H-Si(001) 4keV
Yie
ld
Detector Angle [deg]
H- Si(001) vs H-Si(111)
H- Si(001): assuming dihydride model 1.38x1015 /cm2
Estimate of sensitivity to H: 8×1013 H/cm2
Extrapolated sensitivity to H: 1×1013 H/cm2
Angular dependence
• observe angular dependence of H- fraction• No H peaks at angles above 80o
• Low sensitivity at angles < 60o
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65 70 75 80 85 900
10
20
30
40
50
60
70
H+ F
ract
ion
(%)
Recoil Angle [deg]
104.3 keV Ne+, 1x1 H - Si(111) E
H=5 keV [1]
J.B. Marion, F.C. Young, NRA Tables, 1968.K. Mitsuhara et al., NIMB 276 (2012) 56-67
60 65 70 75 80 850
1000
2000
3000
500 keV Si+
Yie
ld
Recoil Angle (deg.)
EH=2keV
EH=3keV
EH=4keV
EH=5keV
EH=6keV
EH=7keV
Step dose: 0.5 uC
60 65 70 75 80 850
1
2
3
4
5
6
7
8
9
Rel
ativ
e H
- fr
actio
n (%
)
Recoil angle [deg]
500 keV Si+, H-Si(001)E
H=2-7keV
Marion-Young
Best conditions at EH=2-5keV and angle = 70-80o
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ME-ERD for Hf silicate films
Sample Tdep, C #cycles Thickness, nm In-situ RTA
1367 200 16 3.6
1351 300 19 3.6 UHV, 800oC, 30 sec
1355 350 21 3.4
1376 350 60 16
65 70 75 80 850
100
200
300
Y
ield
Angle [degrees]
Tx=200oC
Tx=300oC
Tx=350oC
Si+
H-
Incident beam: 500keV Si+
Incident angle = 45o
Dose = 0.5C
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Summary: Towards “Complete ME-IBA”
We were able to detect hydrogen using ME-ERD using Si(N) incident beams with no modification in TEA
Medium Energy Elastic Recoil Spectroscopy with incident Si, N ions gives complimentary information on hydrogen content
• Hi-Si(001): we observe angular dependence of H- fraction
• The H- fraction is expected to increase with decreasing energy of the recoils (incident energy)
– Damage effects are significant surface needs to be refreshed under the beam
– Uniform lateral distribution is assumed
– Accurate background fit is necessary to get quantitative fitting
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Thank you!Thank you!
