Surface Structure Analysis in Ⅰ ) Low Energy Ion Scattering Ⅱ ) Medium Energy Ion Scattering...
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Transcript of Surface Structure Analysis in Ⅰ ) Low Energy Ion Scattering Ⅱ ) Medium Energy Ion Scattering...
Surface Structure Analysis
inⅠ) Low Energy Ion ScatteringⅡ) Medium Energy Ion Scattering
Simultaneous Determination of Atomic Arrangement
(not only surface atoms but also shallow subsurface atoms)
and Elemental Species of Atoms
by
Specialized form ofIon Scattering Spectroscopy
Ⅰ) Low Energy Ion Scattering
The first idea of Impact Collision Ion Scattering Spectroscopy
(ICISS)
Experimental scattering angle θL is taken close to 180°
for quantitative structure analysis
Fig. 1
M. Aono et al., Jpn. J. Appl. Phys. 20 (1981) L829.
Extension of ICISS to more convenientCo-axial ICISS (CAICISS)
Experimental scattering angle θL is taken just at 180°
for more convenient quantitative structure analysis
Fig. 2
CAICISS apparatus commercialized by Shimadzu Corp.
CAICISS - I
Fig. 4
Fig. 3
CAICISS-I was selected in top-ten Japanese industrial productions in 1991by the Nikkan-kogyoNewspaper.
Power of CAICISS
1) Energy-distribution (spectrum) of scattered ions
2) Angular Dependence of scattered ion intensity
3) Time dependence of spectrum of scattered ions
Time-resolved observation of
dynamic processes
Quantitativeatomic
arrangement analysis
Elemental analysis
of all atoms
Fig. 5
Fig. 6
Fig. 7
22
1
220
22
0
00 sincos
LL M
M
MM
MEE
ab
Method of elemental analysis of surfaces atoms by ion scattering ( in case of CAICISS, θL=180°)
Fig. 8
Time of flight (ns)
Inte
ns
ity
(c
ou
nts
)
F/Ca = 1.0 ±0.2
Composition analysis by CAICISS of a monolayer of CaF2 deposited on Si(111)
Fig. 9
L
a b
Method to determine the shape of shadow cone experimentally by CAICISS
a b
Method to determine the position of atom B relative to the position of atom A by CAICISS
A
B
Inte
nsi
ty o
f io
ns
scat
tere
d f
rom
ato
m B
Fig. 10
Fig. 11
Fig. 12
Structure analysis of TiC(111) surface by CAICISS
Inte
nsi
ty o
f io
ns
scat
tere
d f
rom
Ca
atom
s
Angle
d
0.064±0.005 nm(0.079 nm in bulk)
F
CaSi
(a)
(b)
Structure analysis of CaF/Si(111) by CAICISS
Fig. 13
Structure analysis of Si(111)√3x √3-Ag surface by CAICISS
Fig. 14
Ⅱ) Medium Energy Ion Scattering
Medium-energy CAICISS (ME-CAICISS)
DUOPLASMATRONION SOURCE
X-YSTEERER
EINZEL LENS
ACCELERATIONTUBE
Q-LENS
X-Y STEERER
BENDING MAGNET
COLLIMATOR
CHOPPINGELECTRODE
CHOPPING APERTURE
POSCHENRIEDER ELECTROSTATICDEFLECTOR
MCP
SCATTERED-IONDECELERATION TUBE
SAMPLE
AMPLIFIER CFD
TIME
ANALYZER
PULSEGENERATOR
DELAY
DELAY
(a) Ion beam source in combination with a 100 keV accelerator (b) Beam chopping system
(c) Target on a 3-axis goniometer (d) TOF energy analyzer located at a scattering angle of 180 ゜
(a)
(b)
(c)
(d)
E0 = 100 keV
Subsurface and burried interface structure analysis by ME-CAICISS
Fig. 15
Fig. 16
Sb (δ-doping)
a-Si Si(001)Si
T. Kobayashi et al., Appl. Phys. Lett. 74 (1999) 673
250
200
150
100
50
0
Co
un
ts
520480440400
TOF (ns)
● ■ ▲ ○ □ △
(a)
(b)Sb Si
1.2
1.0
0.8
0.6
0.4
0.2
0.0
No
rma
lize
d y
ield
2520151050
Polar angle (deg)
<001> <017><015>
<014><013>
<012>
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Sb
Si
Fig. 17
(a) (b)
(c)
Co
nce
ntr
atio
n o
f S
b (
%)
302520151050
Depth (nm)
5
4
3
2
1
0
1.0
0.8
0.6
0.4
0.2
0.0
Fra
ctio
n o
f su
bst
itu
tio
nal
Sb
Original position ofδ-doped Sb layer(d)
Annealed at 750 oC
Structure analysis by ME-CAICISS of a Si film with δ-doped Sb (after annealing at 750oC)
25 nm