Diamond Manufacturers
for ATLAS Upgrades
Brief Overview:
Next Upgrade (IBL): Diamond Beam Monitor (DBM)
News from two diamond manufacturers
E6/DDL
II-VI
News from diamond cutting & thinning companies
Summary
March 26, 2012
R. Kass
1
Diamond Beam Monitor
Part of IBL upgrade
– Bunch-by-bunch luminosity monitor (aim < 1 % per BC per LB)
• Finer segmentation & larger acceptance than BCM
• Never saturates
• Internal stability monitoring
– Bunch-by-bunch beam spot monitor
• Need triple-module telescopes for (limited) tracking
• Can distinguish hits from beam halo tracks
• Unbiased sample, acceptance extends far along beam axis
BCM
– Baseline: 4 telescopes of 3 IBL modules per side → 24 total diamonds
– Avoid IBL insertion volume and ID acceptance (η>2.5)
– Place in pixel support structure close to detector and beam pipe
DBM: 3.2<η<3.5
March 26, 2012
R. Kass
2
DBM Diamond Sensor Plan
Diamond Sensors for DBM:
type: polycrystalline CVD diamond
size: 21 x 18 mm2, 525 ± 25 mm thickness
number: 40-45 need for DBM modules
24 + spares
5 for Irradiation studies
Two diamond suppliers involved:
DDL/E6 (UK based)
21 x 18 mm pCVD diamond
II-VI (US based)
2
Some parts already in hand that need
cutting and/or thinning
March 26, 2012
R. Kass
3
Sensors from DDL
Ten Detectors ordered from DDL/E6
(thick E6 wafer – Wafer 9)
– Plan was for wafer to be tested at OSU
→ wafer characterization
→ device selection
– Wafer 9 received from E6 11-Jan-2012
• Rind still attached
• Defect level looks ok
– Wafer 9 returned to E6 - rind removal
– Wafer arrived at OSU, test grid
applied, being testing
March 26, 2012
R. Kass
4
Wafer 9 from DDL
Growth side
Substrate side
5 inches
March 26, 2012
R. Kass
5
Thickness of wafer 9 from DDL
As grown thickness varies from ~1.24 to 1.48 mm
March 26, 2012
R. Kass
6
Collection Distance & Current
Characterisation of DDL’s wafer 9
current (nA)
CCD (mm)
Good regions have I <5 nA at 1000V in air
All regions of wafer 9 look good
We are almost finished measuring the CCD & I in all regions of the wafer
Expect to finish measuring the CCD & ship back to DDL/E6 mid-week
March 26, 2012
R. Kass
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Electric Field Characterisation
of DDL’s wafer 9
Need to take into account the varying thickness of the wafer
Scale previous CCD plot to E=0.66V/mm
This information allows us to make a “cut map”
March 26, 2012
R. Kass
8
Cut Map Example
Based on the CCD and thickness info we divide the wafer into “sensors”
wafer 8
Wafer 8 was cut into eleven 2 x 2 cm2 sensors
March 26, 2012
R. Kass
9
E6/DDL Production Capabilities
Get 10-15 FE-I4 sensors per wafer
Ordered 10 DBM Sensors detectors from DDL’s
wafer 9
21 x 18 mm2 with CCD>200 mm at 1000V
Each piece will be thinned to 525 mm
Expect the pieces to arrive in June
Processing takes 6-10 weeks after return of wafer
Expect to have access to 10-20 wafers/year
determined by the orders we place
March 26, 2012
R. Kass
10
Work with II-VI
II-VI is the
“2nd Company”
5 inches
www.ii-vi.com
II-VI makes
“optical grade”
cvd diamond
laser windows..
Wafer Results
• Can grow thick wafers - 2 mm thick
– grown for another application
• Very good CCD results
– 300 µm @ 0.5 V/µm
• Problems with N2 and growth rate
•
problems showed up at the edges
March 26, 2012
R. Kass
11
Sensors from II-VI
Proceeding to develop additional supplier
of detector grade material based on
their samples
• Good CCD results
– 300 µm @ 0.5 V/µm even though grown for
another application and problems with N2
– Modified growth process
• ATLAS committed to produce one
detector grade wafer by June with option
for second wafer
• Quote received 9-Feb:
specified ccd >250 µm @500µm thickness
• ATLAS placed order for 10 parts with
option for 10 more
March 26, 2012
R. Kass
12
Cutting & Thinning Parts in Hand
Have tested part thinning (750μm→525μm)
– 1cm x 1cm part used, came back fine
Sent first 2cm x 2cm parts for thinning
returned with edge problems
we are looking into a laser trimming repair
looks do-able
Sent: one 2x6 for cutting & thinning
four 2x2’s for thinning
Expect three weeks to get 2x2 parts back
If ok → send remainder of parts
March 26, 2012
R. Kass
13
Summary
Two manufacturers are in place: DDL, II-VI
Three orders of sensors from two manufacturers:
DDL: 11 (wafer 8) + 10 (wafer 9)
wafer 9 being tested
II-VI 10 (with an option of another 10)
looking forward to receiving their pieces in May
CCD measurements on DDL’s wafer 9 just about finished
will ship back to DDL/E6 shortly
Progress on wafer thinning
working with 2 companies in the US
Can now get 100’s of sensors/yr
March 26, 2012
R. Kass
14
Extra Slides
March 26, 2012
R. Kass
15
Introduction: Diamond as sensor
material
Property
Diamond
Silicon
Band gap [eV]  Low leakage
5.5
1.12
Breakdown field [V/cm]
107
3x105
Intrinsic resistivity @ R.T. [Ω cm]
> 1011
2.3x105
Intrinsic carrier density [cm-3]
< 103
1.5x1010
Electron mobility [cm2/Vs]
1900
1350
Hole mobility [cm2/Vs]
2300
Saturation velocity [cm/s]
Density [g/cm3]
0.9(e)-1.4(h)x
0.82x 107
2.33
6
14
5.7
11.9
43
13-20
~2000
150
13
3.61
Radiation length [cm]
12.2
9.36
Interaction length [cm]
24.5
45.5
Spec. Ionization Loss [MeV/cm]
Aver. Signal Created / 100 μm [e0]
6.07
3.21
3602
8892
4401
8323
Dielectric constant – ε  Low cap
Displacement energy [eV/atom]
 Rad hard
Thermal conductivity [W/m.K]
 Heat spreader
Energy to create e-h pair [eV]
 Low Noise, Low signal
Aver. Signal Created / 0.1 X0 [e0]
1
1

 k 
MFP MFP0
480
107
3.52
Atomic number - Z
Radiation Studies
Single-crystal CVD & poly CVD fall along
the same damage curve
Proton damage well understood
At all energies diamond is >3x more
radiation tolerant than silicon
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Radiation Damage - Basics
Radiation induced
effect
Leakage current
Space charge
Charge trapping

Diamond
small &
decreases
~ none
Yes
Operational
consequence
none
Silicon
Operational
consequence
I/V = αΦ
Heating
α ~ 4x10-17 A/cm
ΔNeff ≈ -βΦ
Thermal runaway
β ~ 0.015 cm-1
Increase of full
depletion voltage
Charge loss
1/τeff = βΦ
Charge loss
Polarization
β ~ 5-7x10-16 cm2/ns
Polarization
none
Charge trapping the only relevant radiation damage effect
 NIEL scaling questionable a priori
 Egap in diamond 5 times larger than in Si
 Many processes freeze out
 Typical emission times order of months
1
 eff
  N t (1  Pt ) t vth
t
 Like Si at 300/5 = 60 K – Boltzmann factor
 A rich source of effects and (experimental) surprises !
OSU, Nov 9, 2011
R. Kass: DOE Review
17