Surface Structure Analysis
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Surface Structure Analysis. Simultaneous Determination of Atomic Arrangement (not only surface atoms but also shallow subsurface atoms) and Elemental Species of Atoms by Specialized form of Ion Scattering Spectroscopy. in Ⅰ) Low Energy Ion Scattering

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Surface Structure Analysis

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Surface structure analysis

Surface Structure Analysis

Simultaneous Determination of

Atomic Arrangement

(not only surface atoms but also

shallow subsurface atoms)

and

Elemental Species of Atoms

by

Specialized form of

Ion Scattering Spectroscopy

in

Ⅰ) Low Energy Ion Scattering

Ⅱ) Medium Energy Ion Scattering


Surface structure analysis

Ⅰ) Low Energy Ion Scattering

The first idea of

Impact Collision Ion Scattering Spectroscopy

(ICISS)

M. Aono et al.,

Jpn. J. Appl. Phys.

20 (1981) L829.

Experimental scattering angle θLis taken close to 180°

for quantitative structure analysis

Fig. 1


Surface structure analysis

Extension of ICISS to more convenient

Co-axial ICISS(CAICISS)

Experimental scattering angle θLis taken just at 180°

for more convenient quantitative structure analysis

Fig. 2


Surface structure analysis

CAICISSapparatus commercialized by Shimadzu Corp.

CAICISS - I

Fig. 4

Fig. 3

CAICISS-I was

selected in top-ten

Japanese industrial

productions in 1991

by the Nikkan-kogyo

Newspaper.


Surface structure analysis

Power of CAICISS

1) Energy-distribution (spectrum) of scattered ions

Elemental

analysis

of

all atoms

2) Angular Dependence of scattered ion intensity

Quantitative

atomic

arrangement

analysis

Fig. 5

Fig. 6

Fig. 7

3) Time dependence of spectrum of scattered ions

Time-resolved observation of dynamic processes


Surface structure analysis

Method of elemental analysis of surfaces atoms by ion scattering ( in case of CAICISS, θL=180°)

b

a

Fig. 8


Surface structure analysis

Composition analysis by CAICISS of a monolayer of CaF2 deposited on Si(111)

F/Ca = 1.0 ±0.2

Intensity (counts)

Time of flight (ns)

Fig. 9


Surface structure analysis

Method to determine the shape of shadow cone

experimentally by CAICISS

L

b

a

Method to determine the position of atom B relative to the position of atom A by CAICISS

Intensity of ions

scattered from atom B

A

B

a

b

Fig. 10

Fig. 11


Surface structure analysis

Structure analysis of TiC(111) surface by CAICISS

Fig. 12


Surface structure analysis

Structure analysis of CaF/Si(111) by CAICISS

(a)

Intensity of ions

scattered from Ca atoms

Angle

(b)

F

d

Ca

Si

0.064±0.005 nm

(0.079 nm in bulk)

Fig. 13


Surface structure analysis

Structure analysis of Si(111)√3x √3-Ag surface by CAICISS

Fig. 14


Surface structure analysis

Ⅱ) Medium Energy Ion Scattering

Medium-energy CAICISS (ME-CAICISS)

E0= 100 keV

(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 ゜

POSCHENRIEDER ELECTROSTATIC

ACCELERATION

DEFLECTOR

COLLIMATOR

X-Y STEERER

TUBE

CHOPPING

BENDING

ELECTRODE

MAGNET

Q-LENS

EINZEL LENS

CHOPPING

(a)

APERTURE

X-Y

(b)

PULSE

STEERER

GENERATOR

(d)

DUOPLASMATRON

(c)

ION SOURCE

MCP

SAMPLE

SCATTERED-ION

DECELERATION TUBE

DELAY

TIME

ANALYZER

AMPLIFIER

CFD

DELAY

Subsurface and burried interface structure analysis by ME-CAICISS

Fig. 15

Fig. 16


Surface structure analysis

Structure analysis by ME-CAICISS of a

Si film with δ-doped Sb (after annealing at 750oC)

250

200

a-Si

Si

Si(001)

(a)

(b)

150

Counts

(b)

100

Sb

Si

50

(a)

25 nm

0

Sb (δ-doping)

400

440

480

520

TOF (ns)

Annealed at 750 oC

(c)

1.2

Sb

1.0

Original position of

δ-doped Sb layer

(d)

0.8

0.6

0.4

1.0

0.2

1.2

0.0

Normalized yield

0.8

Si

1.0

<015>

<013>

0.6

0.8

<012>

<001>

<017>

<014>

Concentration of Sb (%)

Fraction of substitutional Sb

0.6

0.4

0.4

0.2

0.2

5

0.0

0

5

10

15

20

25

0.0

4

Polar angle (deg)

0

5

10

15

20

25

30

Depth (nm)

3

T. Kobayashi et al., Appl. Phys. Lett. 74 (1999) 673

2

1

Fig. 17

0


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