Pt(115) - Y. Hwu, D.Y. NohQ.D. - C.-H. Hsu, Y.P. Stetsko
X-ray Microscopy - G.C. Yin, M.T. Tang, Y.F. SongCoherent Scattering – R. Dronyak, Y.P. Stetsko
Keng Liang 梁耕三
National Synchrotron Radiation Research Center
I. Surface X-Ray ScatteringII. Recent Progress on Nano Probes at NSRRC
Grazing Incidence X-ray Scattering
Equilibrium Crystal Shape
An ECS of face center cubic crystal of simple metals
The ECS of platenum. There are (117), (2 2 17), and (1 1 13) facets in addition to the (001) facet.
(Pt)
Magic VicinalsMagic Vicinals
Au (117) Au (115) + Au (1,1,11)
Terrace Width : 3.5 atoms 2.5 atoms 5.5 atoms
Bartolini et. al, Physical Review Letters, 63 872 (1989)
0
1
2
T = 873 K< 115 >
< 552 >
Q
z (r.
l.u.) (002)
(002)
0 10
1
2
T = 973 K
Qx (r.l.u.)
< 115 >
< 552 >
Qz (
r.l.u
.)
0.2 0.40
1 Qz = 0.9
Qx (r.l.u.)
Inte
nsity
(a.
u.)
0.2 0.40
1 Qz = 1.2
Qx (r.l.u.)
Inte
nsity
(a.
u.)
abc
800 1000 1200
1E-3
0.01
0.1
Temperature (K)
Inte
nsity
(a.
u.)
abc
8
12
16
20
(de
gree
s)
< 117 >
< 115 >
< 2 2 17 >
< 1 1 13 >
Peak positions of X-ray reflection measured from a Pt(115) surface. Insets: intensities of X-ray scans in the <-5, -5, 2> direction at a given Qz.
The upper panel: the measured angles of the CTR’s with respect to the <001> direction. The bottom panel: the intensity variations of the <1 1 13> facet and the γ-CTR.
T > 1198 K
T 1073 K
T 1073 K
T 963 K
T 773 K
Schematic surface topologies of the Pt(115) at representative temperatures. The arrows indicated as α, β, and γ are the surface normals.
Uncapped In0.5Ga0.5As Quantum Dots
In0.5Ga0.5As 5.85 ML/ Ga (4x2)
AFM image
n ~ 5 x1010 cm-2
J. Cryst. Growth, 175/176, 777 (1997).
Grown by MEE
aInAs = 6.0583Å aGaAs = 5.65325Å
misatch = 7.2 %
grown @ 520oC 0.7 ML/s.
GaAs buffer layer 200 nm
GaAs (001)
narrow size distribution uniform shape
Issues of Interest
shape, strain, and compositional profile
coherent (dislocation free) dots
Self-assembled coherent QDs grown by MBE
Grazing Incidence Reciprocal Space Mapping of surface Bragg peak
Reproduced from PRL 85, 1694 (2000) by I.Kegel et al.
a) Scattering processes for a particular region of constant lateral lattice parameter at height z above the substrate.b) Simulated intensity distribution close to a surface Bragg-reflection (hk0), RSM.c) f-intensity distribution at the selected iso-strain area. Its height z is calculated from the angle of maximum intensity.
Structure factors for weak “-” and strong “+” even reflectionsStructure factors for weak “-” and strong “+” even reflections
DispersiveDispersive resonant x-ray diffraction techniqueresonant x-ray diffraction technique
Schematic representation of scattering properties of qu
antum dot iso-strain slabs
),()1(),(),,( GaAsInAsInGaAs EFxExFxEF QQQ )],(),()1(),([4 EfEfxExf AsGaIn QQQ
Electron Binding Energies
UV
Soft X-ray
Hard X-ray
Anomalous X-ray Scattering
Chemical composition and/or electronic states
Atomic scattering factor f (q,E)= f0(q) + f’(E)+ i f”(E)= f1+i f2
Intensity
E/Eedge
f1
f2
22
iHKL rqi
iiHKL efFI
Structure factors for weak “-” and strong “+” even reflectionsStructure factors for weak “-” and strong “+” even reflections
DispersiveDispersive resonant x-ray diffraction techniqueresonant x-ray diffraction techniqueExtreme compositional (Extreme compositional (xx) sensitivity of weak reflections) sensitivity of weak reflections
Schematic representation of scattering properties of
quantum dot iso-strain slabs
),()1(),(),,( GaAsInAsInGaAs EFxExFxEF QQQ )],(),()1(),([4 EfEfxExf AsGaIn QQQ
-1.0 -0.5 0.0
1E-4
1E-3
0.01
Energies
-1.2-10
-6.2 -3.7
10.368 keV10.35 keV10.2 keV7.75 keV
qr (nm-1)
Inte
nsity
Radial intensity distributions I(qr) measured f
or several energies of the incident radiation
DAFS measurements of InGaAs/GaAs quantum dotsDAFS measurements of InGaAs/GaAs quantum dots
Theoretical I(E) distributions for weak (200) and strong (400) reflections calculated for different compositions x
10.3 10.4
1
10
100
Energy E (keV)
10.3 10.4
-8
-4
0
4
Ga K-edge
f /
f //
E (keV)
Ele
ctro
ns
x = 0.4 (400)
x = 0.1 (400)x = 0.4 (200)
x = 0.1 (200)
Nor
mal
ized
inte
nsit
y
10.3 10.40.01
0.1
1
10
Energy E (keV)
(0.24; 0.07)
(0.375; 0.05)
(0.48; 0.03)
(0.54; 0.02)
(0.31; 0.06)
(x = 0.13, x = 0.08)
- 0.275
- 0.33
- 0.44
- 0.55
- 0.22
qr = - 0.11 nm-1
Inte
nsity
(a.
u.)
Experimental I(E) distributions measured at different radial qr positions for the weak (200) refle
ction
Height reconstruction of InGaAs/GaAs quantum dots Height reconstruction of InGaAs/GaAs quantum dots
Reconstructed height-dependent distributions of the composition x, lateral lattice parameter a and lateral size S of quantum dots. Region (I) [0 < h < hC] - compressed mate
rial, and region (II) [h > hC] - tensile material.
)/()( GaAsInAsGaAs aaaaa
AFM images of InAs/GaAs(001) quantum rings
Self-assembled InAs/GaAs quantum ringsSelf-assembled InAs/GaAs quantum rings
Electron Binding Energies
UV
Soft X-ray
Hard X-ray
Photon-In/ Photon-Out ExperimentsPhoton-In/ Photon-Out Experiments
Orbital ordering in TMO’s
Orbital ordering in TMO’s
Mn3+
Mn4+
Charge contour of La0.5Sr1.5MnO4
Orbital ordering in La0.5Sr1.5MnO4 is dominated by (z2- x2)/ (y2- z2), rather than (3x2- r2 )/(3y2- r2 ), in contrast to the current understanding.
EPU Beamline (60-1500 eV)
Spin-resolved Photoelectron Spectroscopy Station
Soft X-ray Magnetic Scattering Station
PEEM Station
Charge, Spin, Orbital, LatticeCharge, Spin, Orbital, Lattice
Low EmittanceLow Emittance
TLS(1.5 GeV)
Beamline
國際間中、高能量同步加速器光源設施
( ): distributed dispersion 1: separated function, nonlinear optimization is under study 2: combined function, nonlinear optimization is under study
931104-15
同步加速器設施聚頻磁鐵光亮度比較(TLS, TPS, Diamond, SLS, SPring-8)
Lateral resolution [nm]
Ch
emic
al in
form
atio
n
A. Hitchcock
Photoelectrons, Spectromicroscopy Nano Fabrication
XY ScanController
U5 Undulator Refocusing Mirror
SGMPinhole
Order Sorting Aperture
Zone PlateSample Flexure Stage
e-
h
x y
e-
e-
Schematic of SRRC-SPEM at U5 Beamline
W. Yun
Fresnel Zone Plates
SPEM
X-ray microscope in development
Zone Plate
Focus
Zone Plate Zone Plate EquationEquationss
rrnn = ( = ( n n ff ))1/21/2
ddmm = 1.22 = 1.22ddrrn n //mm
f : f : focal lengthfocal length nn : : zone index zone index : wavelength: wavelength mm : diffraction order : diffraction order r : radius of the zone plater : radius of the zone plate drdrnn: outermost zone width: outermost zone width
ffmm = = 2 r dr / 2 r dr / ((mm ))
Spatial ResolutionSpatial Resolution
Zone Radius Zone Radius
Focal LengthFocal Length
Numerical ApertureNumerical Aperture NA NA = = / ( / (2 dr)2 dr)
When NA <<1, the ZP can be treated like an ordinary refractive lens, When NA <<1, the ZP can be treated like an ordinary refractive lens, i.e., 1/q + 1/p = 1/f and M = p/q.i.e., 1/q + 1/p = 1/f and M = p/q.
Zone plate consists of concentric rings (zones) with zone width Zone plate consists of concentric rings (zones) with zone width decreasing with radius. decreasing with radius.
Zone plate optical systemZone plate optical system Condenser TubeCondenser Tube
Monochromatic X-raysMonochromatic X-rays
Nano-TXM (optical)Nano-TXM (optical)
10 cm
Ion ChamberIon Chamber
Phase RingPhase Ring
Sample mount and sample Sample mount and sample manipulation systemmanipulation system
CondenserCondenser
Experimental Experimental Hutch wallHutch wall
Source : SWLS, 5T, Source : SWLS, 5T, EcEc=7.5 kev=7.5 kev
FM : MFM : M1/11/1
DCM : Ge(111) DCM : Ge(111) E/E E/E 10 10-3-3
EE=8-11 keV =8-11 keV
SampleSample
Objective Zone PlateObjective Zone Plate
CCD CCD
Beam StopperBeam Stopper
I0 monitorI0 monitor
Phase RingPhase Ring
PinholePinhole
Optical Layout of NSRRC nano-TXMOptical Layout of NSRRC nano-TXM
Phase contrast helps.Phase contrast helps.
E(z)=E0e-i2(--i) z/ =E0ei2z/ -2z/
I(z) |E(z)|2 I0e4z/
Absorption contrast z= 4z/ 3
Phase contrast(z)=2z/
zRefraction index : n = 1--i
Hendrickson Criterion
Water window
G. Schneider (1998)Schematic of Zernike phase contrast.
Result (1)~First orderResult (1)~First order
Inner line width: 50nm
Tested At 8 & 11 keV
Exposure time: 15 secs
Resolution: Better than 60nm
Spoke pattern
Fov: 15um x 15um
3um
At 8 and 11 keV
Exposure time: 15 mins
Resolution: Better than 30nm
Fov: 5um x 5um
5um
Spoke pattern
Result (2) Third orderResult (2) Third order
3um
5um
Phase retrieval of diffraction patterns using the oversampling method
Iterative phase retrieval algorithm
Sayre D., Acta Crystallogr. 5, 843 (1952).Gerchberg R. Saxton W., Optik 35, 237-46 (1972).Fienup J., Opt. Lett. 3, 27-9 (1978).Miao J. at al., Nature. 400, 342-344 (1999).
Importance of phase information
1 object
2 object
FFT
FFT
Intensity
Intensity
Phase
Phase
FFT -1
FFT -1
Simulated case
Simulated X-ray diffraction pattern
2D object
Examples of images retrieved using iterative phasing method with labels showing the number of iterations in each image
i = 10 i = 100
i = 250 i = 500
3D imaging of nanostructuresJohn Miao et al., Phys. Rev. Lett. 89, 088303 (2002).
(a) A SEM image of a double-layered sample made of Ni (~2.7 x 2.5 x 1 m)
(b) A coherent diffraction pattern from (a) (the resolution at the edge is 8nm)60×60 area of missing data at the center
(c) An image reconstructed from (b) An iso-surface rendering of the reconstructed 3D structure
用戶年會參與人數趨勢圖
0
50
100
150
200
250
300
350
400
450
500
550
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
年份
人數
0
25
50
75
100
125
150
175
壁報數
0
5
10
15
20
25
30
Num
ber
of b
eam
lines
1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 20080
20
40
60
80
100
120
140
160
180
200
Bio.
Total
I.F. > 2
Num
ber
of p
ublic
atio
ns
year
量的方面 : SCI 論文總數 200 生物領域 30%
質的方面 : Impact Factor > 6 10% > 2 60%
預計至 2008 年達成之目標
論文成長與光束線數成正比用戶成長潛力即將受限於設施之飽和
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
0
2
4
6
8
10
12
Bio.
Total
I.F. >6
Year
X-ray Research
Year
1994 1996 1998 2000 2002 2004 2006 2008
No.
of
oper
atio
nal b
eam
line
0
2
4
6
8
10
12
14N
o. o
f pu
blic
atio
n
0
20
40
60
80
100
I.F. >2
superconducting IDs