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