1. Progress on single crystal diamond beam position monitors for
Progress on single crystal diamond beam position monitors for synchrotron X-ray beams
J Morse1, M Salomé1, K Detlefs1
H Graafsma2
K Desjardins3
M Pomorski4
B Solar5
E Berdermann6
J Smedley7
1European Synchrotron Radiation Facility, Grenoble, 38043, France
2Deutsches Elektronen-Synchrotron, Hamburg, 22607, Germany
3Synchrotron Soleil, L'Orme des Merisiers -Saint Aubin, 91192, France
4Commissariat à l'Energie Atomique …, Gif s/Yvette, 91191, France
5Dromedar d.o.o., Žabnica, 4209, Slovenia
6GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, 64220, Germany
7Instrumentation Division, Brookhaven National Laboratory, Upton, NY, USA

2. 1. Synchrotrons and X-ray beam monitoring needs:
Outline
1. Synchrotrons and X-ray beam monitoring needs:
why diamond? why single crystal?
CVD single crystal diamond bulk- and surface- challenges
quadrant- and resistive-electrode devices:
principle of operation; fabrication;
‘near dc ’ (electrometer) and RF readout methods
5. 'superthinning’ project
6. Conclusions / status 2

3. synchrotron sources:
Now (2012) about 50 major X-ray synchrotrons in the world…
sources of infra-red to MeV photon beams, but main interest 1 ~ 100keV
the big three, commissioned early 1990's…
ESRF-Grenoble, France
APS-Argonne nr. Chicago
SPring8, Harima nr. Osaka 3

4. synchrotron sources: situation in 2012
J-L Revol, ESRF (ASD)

5. 3rd generation synchrotron beamlines
~ 45 beamline stations
ESRF Ø300m
energy tunability
undulator source
ΔE/E ~10-2
‘white’ X-ray beam
50~100m source to
end station
pink/white beam
monochromatic
X-ray beam out
Bragg diffraction from silicon crystals
ΔE/E ~10 -4
flux on sample
~1013 ph/sec
beam position - intensity monitors
white/pink beam 0.1~1kWmm-2
monochromatic beam ~mW

6. X-ray beamline monitoring goals
required beam stability ~10% of 0.1 ~ 50μm beam size
NINA upgrade beamline, nanofocusing → 10nm beam on sample
measurements ~dc (thermal drifts) to ~ 1kHz (acoustic vibrations)
Position
accuracy & linearity requirement typically ≤ 1% (sometimes <0.01% ratiometric)
Intensity:
(sub) millisec sampling; pump probe synchronization <100psec
Timing:
continuous signal readout with negligible beam interference:
absorption, coherence loss, scattering
beamline compatibility:
package size, operation in air, dirty-vacuum, clean-UHV
lifetime >months under ionizing radiation loads to >104 Gray/sec
device…
crystal monochromatized beams : device absorbed X-ray power ≤ few mW
but beam powers to 100Wmm-2 (C-W) in undulator ‘white’ beams:
heat load → ONLY possible with diamond 6

7. …at energies >20keV, short range of Compton-electrons
why diamond ?
Z = 6 → low X-ray absorption by photoelectric effect … ~8-fold less than silicon for 10keV X-rays
…at energies >20keV, short range of Compton-electrons
5.5eV bandgap
→ ‘zero’ leakage current at room temperature and at high E-fields
→ nanosec pulse response times
→ insensitive to ambient light, (λc ~ 215nm )
‘all diamond’ devices are (X-ray) radiation hard --no atomic displacement damage
extreme thermal conductivity:
diamond ~2000 Wm-1 °K-1 at 273°K , cf. silicon ~150 7

8. quadrant diamond X-ray beam monitor: principle
photocurrent readout of beam position and intensity → simple, compact devices
high purity diamond plate ~10…100µm thick
metal surface electrical contacts ~100nm thick ( e.g. Al, Pt, W)
externally applied bias field 0.5 ~5 Vµm-1
surface
contact
beam
DIAMOND
directly intercepting beam, diamond bulk acts as solid state ‘ionization chamber’
electron thermalization range a few µm for <20keV X-rays
photocharge drifts for ~ nanosecond in applied E field to electrodes
charge cloud lateral thermal diffusion ~10µm
→ induced signals can be measured with 'integrating'
electrometer (charge), or drift current pulses observed directly (wideband)
…beam 'center of gravity' determined by interpolation

9. why not polycrystalline diamond?
attractive: 6" wafers available
→ easier, cheaper device processing
XBIC: signal current map made from x, y raster scan of sample with a ~7keV micron-focused X-ray beam
LIST-CEA Saclay data (ESRF ID21)
but
crystallite grain-boundaries of size ~ 10% of film growth thickness
→ random crystallite orientations
'powder ring' X-ray scattering…
→ local field distortions and charge trapping
& signal response lag
→ random crystallite orientations
'powder ring' X-ray scattering…
→ local field distortions and charge trapping
& signal response lag 9

10. polycrystalline diamond: trapping and signal lag
signal decay after beam cut off
Charge collection efficiency ~1…10%,
variable (prompt + detrapped components) with applied E field 1…5 V/µm,
10 sec
SLS MX beam 15 x 100µm2, x 1012 ph/sec at 12keV
data Ralf Menk, 2006: polycrystalline ~10µm thick, grown on Si substrate by Diamond Materials GmbH, Freiburg, contacts fabricated at PSI Nanofab (?)

11. electrical responsivity with X-ray energy
Carbon K edge feature is field dependent,
caused by incomplete carrier collection for near surface absorption
Platinum electrodes M edge feature:
photons absorbed by incident contact
(no field dependence observed)
J. Keister and J. Smedley, NIM A 606, (2009), 7

12. signal linearity with beam flux
Linearity at high currents, single crystal diamond with Pt electrodes
(measurements at BNL NSLS-X28C white beam, absorbed power density up to 20 Wmm-2)
at ESRF, signal linearity observed over range ~10pA to >10µA
(monochromatic beams, keV data)
→ operation in linear mode shown over
total >10 orders magnitude
ESRF ID21 microbeam, 7keV
20nm+20nm - GSI Cr-Au contacts
10pA
1.E - 08 07 06 05 04 03 02 01
1.E+00
1.E+01
power Absorbed by Diamond (W)
Gas ion chamber calibration
Calorimetric calibration
Fit, w = /
0.2 eV
diamond signal (Amps)
J. Bohon, E. Muller, J. Smedley,
J. Synch. Rad 17, (2010) 12

13. position measurement: multiple electrodes:Y X A B C D
exploits diffusion splitting (~10µm) of charge
between A, B, C, D contacts of quadrant motif
→ difference/sum of currents A, B, C, D
gives beam 'centre of gravity’ *
→ sum of currents gives beam intensity
*requires high signal/noise !
Packaged device,
ESRF ID09B, ID11, Desy tests

14. position measurement: resistive contacts
signal current is shared between edge strip electrodes as ratio of resistances through
resistive contact
→ linear position response possible
over several millimeters
→ true beam center of gravity, so
position sensitivity independent of
beam size variation
signal/noise may be limited by contact resistance,
slower response (RC ~µsec)
first device used in
ESRF & Soleil beam tests ~2009

15. quadrant designs: contact fabrication
~100nm Al contacts on
30 and 100µm diamonds
OSU-Kagan
~100nm Al contacts on
100µm plates
INEX, UK
Inex - ESRF - DESY
RF readout design
DIC microscopy
white light microscopy
Lift-off lithography:
cf. shadow mask deposition:
-allows complex geometric designs for metal contacts;
-multiple designs on single mask;
-electrode features to < 1µm
…but difficult work on small samples
-surface preparation, hot acid cleaning and
post-clean handling
- edge ‘beading’ of spin deposited resist
ESRF-DESY-OSU XBPM and microdosimetry mask set , 2010

16. single crystal I-V response in X-ray beam
ESRF ID21 beam ~0.6x1.5µm2, ~4x109ph/sec at 7.2keV,
cross polarizer-selected e6 plates, two-side ion beam etched to final 100µm thickness,
100nm Al sputtered contacts using lift off lithogaphy (OSU-Kagan, 2010)
full charge collection for >10V bias (0.1Vµm-1)
dark leakage current <0.1pA (measurement sensitivity limit) at 200V bias
no hotspot defects found over 7mm2 contact areas for 3/3 preselected samples tested
calibration relative to silicon diode
→ εDiamond = /-0.2 eV/e-h pair

17. position response of diamond quadrant devices
signal slope ~0.5% /micron
beam collimated 200µm 1 2
Line 7.2keV
For large beamsize (> 50µm), device ‘crossover response’ is simply the line integral across the beam intensity profile 1 2
ESRF ID21
electrometer ‘charge integral’ measurements,
i.e. signal integration time >> charge carrier drift time
signal slope ~5% /micron
…beam focused <1µm
isolation gap ~120µm
For a small beam (< 5µm), crossover response is ~independent of beam size:
convolution of
photoelectron thermalization range and
lateral charge diffusion occurring during carrier drift

18. beamline tests : position timescan and ‘vibrations’,
4.4 hours
synchrotron orbit shifts, or something upstream on beamline…
ESRF ID09B, single bunch mode (355kHz)
charge generated in diamond ~ 0.1pC/pulse
currents measured by Keithley 485 electrometers
(10Hz BW, mean current measured ~10µA/contact)
390um thick diamond sample ‘S361-1’ with TiW quadrant contacts inserted before final slitbox, pink undulator beam peaking at 20keV

19. compact diamond mounting
ESRF-ID21 Fluorescence Microscopy beamline: limited space, operation in dirty vacuum and in air
IBM-etched e6 single crystals 4.2 x 4.2mm2, thicknesses 30 & 100µm
guard-ringed direct PCB
mounting with …
… Al electrode contacts and wire bonding (Kagan – OSU 2010)
Rogers multilayer PCB,
microcoax wire leadouts
homogeneous response map
for 3/3 samples tested, no signal ‘hot spot’ defects
<0.1pA leakage current at 2Vµm-1
vertical streaks are from beam Io
normalization errors during scan
ID21 beam line
installation
o scan stage
sample x,y piezo stage f
ocused beam
diamond
quad r a n
t B P M
10mm

20. quadrant device, electrometer readout: time scans
σ =13.3nm
1sec V-F
σ= 20.4nm sec V-F
ESRF ID21 FZP microfocus beam tracking 1sec/point:
vertical beam jumps on synchrotron e-beam refills
5000
10000
15000
20000
25000
30000
35000
-1.5
-1.0
-0.5
0.0
0.5
1.0
position* ( µm )
time (sec)
vertical
horizontal
*scaling 'calibration' error possibly ~10%
~40% synchrotron
refill
2010 data, 4x109ph/sec at 7.2keV (FZP → K-B mirror)
14(18)nm vertical(horizontal), 1sec integration
33(48)nm, 0,1 sec integration
X-ray flux ~108 ph/sec at 7keV (FZP optic):
~ 20fC in diamond per X ray bunch
~ 10nA ‘dc equivalent’ signal current 20

21. ID22 nanofocus beamline: stability measurements
5-6 Sept 2012:
25µm x
17keV beam nnx 1010 ph/sec
23:00, successive time scans:
blue data: beam focused (~50nm) on diamond 'sample'
red data: diamond axially displaced 5mm
17keV, flux 2.5x 109 ph/sec
17keV, flux 2.5x 109 ph/sec

22. ID22 nanofocus beamline: stability measurements
17keV, flux 2.5x 109 ph/sec
2.5nm rms
3.9nm rms
short term vertical and horizontal stabilities
17keV, flux 5.0 x 109 ph/sec
(16 bunch mode)
Keithley 485 electrometers, 100msec integrations at ~1.6sec intervals
diamond piezo stage step-displaced vertically:
10nm steps clearly visible
quasi-linear crossover
response over ~8µm
beam absorption in diamond 1.8% (~70% via photoelectric effect)
measured quadrant currents sum <i > 13nA (ESRF 16 bunch mode, peak pulse currents ~2µA)
for photoelectric absorption,
i = ɸ x Exray / ε (Amps) ɸ = absorbed X-ray flux;
EX-ray = photon energy (eV)
ε = diamond e-h pair production energy = 13 eV

23. ‘resistive contact’ BPMs
40µm e6 plate, with sputtered diamond-like carbon (DLC) contacts (CEA-LIST, M. Pomorski),
ESRF-ID06 beam test:
I-V response in 10.5keV beam, ~1011 ph/sec
(~0.5µA measured photocurrents)
metal electrodes Al, TiPtAu
complete charge collection for bias >5V
non-injecting contact
(measured to +/-100V)
DLC resistive layer
intrinsic diamond slab
DLC resistive layer
metal collecting electrodes
DLC resistive layer
resistivity of contacts ~`20kΩ/square, physically hard and scratch resistant layers 0.2µm thickness
long term radiation, temperature stability…?

24. resistive contact BPM: device #2 at ESRF-ID06
Position noise of first device tested at ESRF measured was limited by the 20kΩ resistance of the DLC contacts (electrometer input voltage noise driven currents)
new device installed at ID06 June 2012, 265µm thick, kΩ resistance contacts
shadow-mask Au electrodes over full-surface DLC
PCB mounted over hole and electrodes connected by Ag loaded thermoplastic
signal current reaches a well defined plateau corresponding to complete photo-charge collection.
excess signal current and noise seen with >100V 'negative' bias
-->local diamond bulk defect(s)
device works perfectly with positive bias…

25. performance, device #2 at ESRF-ID06
beam 12keV, 1.3x 1013ph/sec, ~25x25µm2
device linearity across entire 2mm spacing between the gold line contacts
~zero horizontal-vertical crosstalk
(orientation alignment errors?)
x,y mesh plot shows uniform response over most of the 2x2 mm2 active area: no local defects.
differences between red and blue data points are from beam vertical position drift occurring during two x,y mesh scans of the BPM.

26. duo-lateral Resistive Electrode, position resolutions
device #1, 20 kΩ contacts, 40 µm thick diamond, S/N ~104 (electrometer offset induced noise limit)
active area 2 x 2 mm2, 100msec integrations
[µm]
ID06
σ = 258nm
Proxima2
1 MΩ contacts, 300µm thick diamond, S/N ~105, active area 2.5 x 2.5 mm2, 100msec integrations
σ = 27nm

27. narrowband RF readout: Libera Brilliance1 2 3 4
beam X, Y, Σ out
over fast network
pulse
signals in
~500 systems installed at ESRF + DESY
for electron orbit stabilization using capacitive pick-up buttons
analog stage: SAW narrowband tuned filter (352MHz ESRF, 500MHz DESY)
digital sampling at 110MHz, FPGA digital filtering → output data stream ~130ksample/sec
'rotating' crossbar RF switch removes electronic drift between A,B,C,D input channels 27

28. narrowband RF readout, first tests
Quadrant electrode device first test at DESY-DORIS F1 (white bending magnet, Al filtered beam
May 2012 monochromatic beam tests at DESY P11 with 100µm thick plate
higher field, thinner plate
→ shorter transit times ( <2ns )
signal vs. detector bias
(390µm thick sample, 50µm isolation gap
550V
217V
138V
electrode ground bounce crosstalk
!! with Libera brilliance system, measure 'narrowband' (~5MHz BW ) power at 500MHz center frequency
→ only measure ‘ fast drift’ signal components

29. Libera dynamic position response
first test at DESY Doris synchrotron white beam (filtered bending magnet F4)
stability timescan (Libera ADC buffer data, 130KHz readout digital sampling-averages)
rms position noise* vs. bandwidth µm in
ground shock
position noise includes real beam-sensor movements
J. Morse, B. Solar and H. Graafsma, J. Synchrotron Rad. 17, 456‐464 (2010)

30. RF readout tests DESY Petra P11 (May 2012)
Tests of series of 8 quadrant BPMs (OSU- and INEX-fabricated Al electrodes)
beam vibrations measured 30m from monochromator with bad LN cooling turbulence
quadrant BPM on PCB with 500MHz LC resonators and transformer cable impedance matching
beam
~ 50x100µm2
~1013 ph/sec, 10.0keV Si
diode
diamond BPM-1
diamond BPM-2
time (secs)
130 ksamples/sec (digital averages)
(A+B-C-D)/(A+B+C+D)
BPM 1 BPM2 Q1 Q2 Q3 Q4
20mV, 5ns /div
DSO traces,
'wideband' after 500MHz LC filter
x, y raster scan of electrode
responses, Libera data (sum map)

31. Superthinned diamond membrane beam monitors
DDK scaife-polished optical grade CVD single crystal
(optical grade material!)
selected for low wedge error
cental area thickness ~3µm
after ArO etching
membrane survived boiling acid clean and Al electrodes deposition
ceramic mounting/wire bonding
(Systrel, Paris)
tested at Soleil Synchrotron
October 2012
see talk of Michal Pomorski, this workshop
40µm thick plate shows significant trapping
– I-V plot with X-ray beam shows no plateau region …
…but 7µm membrane area has a good I-V plateau ,
i.e. bulk trapping in membrane is at ‘acceptable’ level
fast response and no polarization effects seen
can we use material with ~ppm N impurity ??

32. conclusions / status / future:
for intensity and position measurements, ‘proof of principle’ now well established by several groups
using quadrant devices, with electrometer or RF signal readout approaches
quality of CVD single crystal material --threading dislocation clusters-- remains a serious limit on
device yield (bad samples shows high dark signal currents and local signal ‘gain’ effects…)
Element Six ‘electronic grade’ samples have not improved over past ~7 years
→ selection of material still necessary to avoid local 'hotspots'
ongoing work:
- testing / deployment of devices: electrometer readout at ESRF; Soleil… RF readout at Petra; NSLS-BNL
- investigating commerical fabrication (INEX; Micron; …) for series production of 'standard' device(s)
and sourcing of superthin plates <10µm by deep dry etching
- robust contacts and devices: - DLC variants for resistive contacts
- boron doped CVD overgrowth
- passivation (Al3N4; SiOx …?) 32

33. Thank-you for your attention