X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

Combination of Scanning Probe Microscope

and X-rays for Detection of Electrons

DHEZ Olivier†, COMIN Fabio‡, FELICI Roberto†, CHEVRIER Joël*, RODRIGUES Mario‡,*

†OGG-INFM, Grenoble, France, ‡ESRF, Grenoble, France, *UJF/CNRS, Grenoble, France.

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

FP6-STREPESRFEuropean Synchrotron Radiation Facility, Grenoble, EUDr. Fabio Comin (coordinator)

GPEC/CNRS Université de la MéditerranéeUMR 6631 CNRS, Marseille, FranceDr. Daniel Pailharey

LEPES/CNRSLaboratoire d'Etudes des Propriétés Electroniques des SolidesCNRS, Grenoble, FranceProf. Joël Chevrier

ISSPInstitute of Solid State Physics, University of Latvia, Riga, LatviaDr.Hab. Juris Purans

UNITNDepartment of Physics, University of Trento, ItalyProf. Giuseppe Dalba

UNITAInstitute of Physical Chemistry and Institute of PhysicsUniversity of Tartu, EstoniaDr. Väino Sammelselg

OGG/INFM/CNRIstituto Nazionale per la Fisica della Materia, Grenoble, ItalyDr. Roberto Felici

IFN-CNRInstitute for Photonics and Nano-technologies, Section "ITC-Cefsa”Trento, ItalyDr. Francesco Rocca.

Project:NMP4-CT-2003-505634

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

Scientific Cases

Topological information

Chemical informationElectronic information

X-rays needed

Nano system

Force interactionNano-manipulation

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

Tip surface distance control

b. Perpendicular• Good capacitive coupling• Possibility to do EFM• As well as SCM

Tuning Forks:Piezo-electricQ Higher than 10 000 without any tipAllow very small amplitudes < 1nmNo laser

A tip must be glued

a. Parallel• Weak capacitive coupling• Possibility to do SCM• No possibility of EFM

Distance regulation: frequency shift - PLL regulation+PID

4mm

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

Setup

X-rayBeam

FluorescenceDetector

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

Microscope

XYZ direction coarse approachAttocube Systems

(Travel:4mm, Res: 25nm)

XYZ direction fine movement(Travel:9µm, Res: 0.02nm)

Tuning Forks system

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

Metallic Tips

NaOH chemical etchedCurvature radius: 10-100nm

50 nm

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

Images CapabilitiesSTM Images AFM Images

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

Experiment IGoal:Photoelectron detection.Detection chain validation.Simulation - experience comparison

Method:Faraday cup design.Lock-in detection.

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

Photo-Electron Yield simulation

-Monte Carlo codes: EGS4 and PenelopeLimitation: do not follow the slow electrons EGS4 >1keVPenelope >100eV. Gold on Copper

Flux: 108 ph/s 800

850

900

950

1000

1050

1100

1150

13 13.5 14 14.5 15

Cur

rent

(fA)

Energy (keV)

~200 fA

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

Gold layer on Copper - L

600

650

700

750

800

850

900

13.6 13.65 13.7 13.75 13.8 13.85 13.9

Me

asu

red

cu

rre

nt

(fA

)

Incident energy (keV)

2 Au Edge

~180 fA

I0=~108 ph/s

Experiment ResultsExperiment parameters:

Monochromatic Beam (1x3 µm)BM05 - I0=108 ph/s - E=13.7 keV (L2 edge of Au)

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

Experiment II

PLL controller+ frequency detector

PIController

Lock-inamplifier

X-rays

Beam Chopper

Excitation

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

Tip Alignment

Si

Ge

W

Ge Kβ: 9.88 keV W Lα: 8.39 keV 0

5e-06

1e-05

1.5e-05

2e-05

2.5e-05

3e-05

3.5e-05

4e-05

-4 -2 0 2 4 0

20

40

60

80

100

120

140

160R

(A

)

Ph

ase

(D

eg

ree

)

displacement (µm)

Lockin RLockin Phase

➀

➁

➀

➁Vertical displacement (µm)

0

200

400

600

800

1000

1200

1400

1600

0 50 100 150 200 250 300

Flu

ore

sce

nce

(A

.U.)

Ge KW L

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

Experiment ParametersSetup:ID22 Beamline ESRFFocusing device: Kirk-Patrick Baez.

Beam characteristic:Monochromatic Beam Size: 2x3 µm2

Incidence angle: ~5ºI0=6.1011 ph/sE=11.1 keV (K edge of Ge)Sample-Tip distance: ~10nm

Ge dots on Si

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

Simulation

-5

0

5

10

15

20

25

30

35

10.6 11 11.4 11.8 12.2 12.6

Cu

rre

nt

(pA

)

Energy (keV)

Code: EGS4Ge Dot on Si waferGe dots

Si wafer

X-Ray Beam

Ge dot R=36nmSi layer l=10µm

Flux: 1012 ph/s

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

-150

-100

-50

0

50

100

150

11.08 11.1 11.12 11.14 11.16 11.18 11.2 11.22

Phase (

Degre

)

Energy (keV)

XANES

AFM (sample/tip) regulation:10 nm during the measure

Noise Level: few fA

Simulation with EGS4 for Ge dots on Si: Ijump=28pA

80

100

120

140

160

180

200

220

11.08 11.1 11.12 11.14 11.16 11.18 11.2 11.22

Tip

Curr

ent

(pA)

30 pA

0

0.5

1

1.5

2

2.5

3

3.5

11.08 11.1 11.12 11.14 11.16 11.18 11.2 11.22

Ge F

luore

scence s

ignal (a

.u.)

Energy (keV)

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

Conclusion

A home built microscope compatible with X-rays synchrotron instrumentation.

AFM-STM Imaging Capabilities

We shows sensitivity to photo-excited electrons.

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

What Next

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

Coaxial Tips Why ?

I

ConductiveTip

Conductive

Layer

insulator

Sample

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

Coaxial Tips development

Tungsten Wire (250µm),Chemical Etched.

Parylene film (~1000Å)

Gold layer (~1000Å)

End opening (FIB)

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

Other development

Implementation on beamline• Imaging capability.➙ Resolution: 50 nm.

Noise problem:- Mechanical noise (Pump, ...)- Electronic Noise.

Collaboration with ID1

Nov 17, 2005 - ESRF, GrenobleX-Tip Workshop

X-Tip Workshop Nov 17, 2005 - ESRF, Grenoble

Acknowledgment

Mario Rodrigues, Daniela Besana, Tiziana Pro, David Loi, Fabio D’Anca, Monique Navizet, …

EU Funding: FP6 Project:NMP4-CT-2003-505634