1Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPP

Charge Collection in p-type Si Tracking Detectors

M.K. Petterson, R.F. Hurley, K. Arya, C. Betancourt, B. Colby, M. Gerling, C. Meyer, J. Pixley, T. Rice, H. F.-W. Sadrozinski

SCIPP, UC Santa Cruz ,1156 High St., Santa Cruz, CA 95060

1) LHC Upgrade environment2) C-V and CCE after Proton/Pion Irradiation 3) Annealing after neutron irradiation4) Bias Dependence of collected charge5) Efficiency

2Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPPFluence in Proposed sATLAS Tracker

sATLAS Fluences for 3000fb-1

1.E+12

1.E+13

1.E+14

1.E+15

1.E+16

1.E+17

0 20 40 60 80 100 120

Radius R [cm]

Flu

en

ce

ne

q/c

m2

All: RTF Formulan (5cm poly)pionproton

ATLAS Radiation Taskforce http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/RADIATION/RadiationTF_document.html

5 - 10 x LHC Fluence

Mix of n, p, depending on radius R

Pixels

Radial Distributionof Sensors determined by Occupancy < 2%

ShortStrips

LongStrips

Design fluences for sensors (includes 2x safety factor) :Innermost Pixel Layer: 1*1016 neq/cm2 Outert Pixel Layers: 3*1015 neq/cm2 Short strips: 1*1015 neq/cm2 Long strips: 4*1014 neq/cm2

Strips damage largely due to neutrons

Pixels Damage due to neutrons+pions:need high fluence proton irradiations

3Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPPRD50 Test Sensors

RD50 Common Micron (6”)

4” : Micron CNM IRST

ATLAS Upgrade HPK (6”)

4Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPP

RD50 MICRON 6” project

MCz (n-p) MCz(n-n), (p-n) Fz (n-p) Fz (n-n), (p-n)

V(FD) [V] 520 220 75 95

Resitivity 1.9 kcm 1.4 kcm 13 kcm 3.3 kcm

Orientation <100> <100> <100> <100>

Neutron and Proton and Pion (Aug. ’07 ) irradiation of SSD and Diodes

•36 processed , 20 received•Fz (Topsil) and MCz (Okmetic) wafers of p&n type material•n-on-n, n-on-p, p-on-n structures (pixels, strips, diodes)

Strips: ATLAS strips geometry 80 m pitch (w/p~1/3)Pads: 5 x 5 mm2 , multiple guard rings

5Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPPCharge collection CCE in p-type MCz

after Proton IrradiationMedQ vs. Bias

0

0.5

1

1.5

2

2.5

3

3.5

0 200 400 600 800 1000

Bias Voltage

Med

Q [

fC]

2552-6-9-1 n-on-pMcz 1.3e14

2552-7-13 N-on-P MCz(Micron) Pre-rad

Curious: large loss of charge at small fluence

6Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPP

Bias Dependence of Efficiency, CCE, Singles Proton Irradiation 1.3e14

eff @ 1fC

0

0.2

0.4

0.6

0.8

1

1.2

0 100 200 300 400 500

MedQ

0

0.5

1

1.5

2

2.5

3

0 100 200 300 400 500

Saturation:Efficiency before Median pulse heightMedian pulse height = Single rate

Efficiency @ 1 fC

Median Charge

Count Rate @ 1 fC

7Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPPC-V and CCE in MCz (Protons 1.3e14)

CV comparison

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0 50 100 150 200 250 300 350 400

Bias Voltage [V]

1/C

[1/

pF

]

C/1

MedQ norm

Agreement between low T– Low f 1/C-V and CCE less perfect than seen before in n-type FZ

SMART p-on-n FZ 187

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 200 400 600 800Voltage [V]

Co

llec

ted

Ch

arg

e [

fC]

1/C 10kHz;+ 22°C1/C 10kHz; -11°C1/C 400Hz; -11°CCharge median value

M.K. Petterson et al., NIMA 583, 189 (2007)

C-V taken at -20oC and 450Hz

1/C overestimates the depletion voltage

8Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPP

p MCz proton irradiation

0.0E+00

5.0E-05

1.0E-04

1.5E-04

2.0E-04

0 100 200 300 400 500 600 700

Bias Voltage [V]

1/C

^2

[1/p

F^

2]

pre-rad1e 14proton

4e 14proton

Protons & P-type: Compare FZ and MCz

p-type FZ:Monotonic Increase in Full Depletion Voltage:Monotonic Introduction of AcceptorsMaterial becomes more p-typeIntroduction rate not constant? Donor removal?

p FZ: proton irradiation

0.E+00

2.E-04

4.E-04

6.E-04

8.E-04

0 100 200 300 400 500 600 700Bias Voltage [V]

1/C

^2

[1/p

F^

2]

pre-rad1e 14proton3e 14proton

p-type MCzNon-Monotonic Increase in depletion voltage:Introduction of DonorsMaterial becomes initially more n-type: Type inversion?Large initial donor introduction rate

9Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPPPions & P-type: Compare FZ and MCz

Micron: 1e14 Pion Irradiated SSD

0

0.0001

0.0002

0.0003

0.0004

0.0005

0.0006

0.0007

0.0008

0 100 200 300 400 500 600 700

Bias Voltage [V]

1/C

[1

/pF

]

pre-rad 3-1 2551-2

p FZ 1e14 3-1 2551-2

p MCz pre-rad 2552-6

n-p MCz 1e14 3-4 2552-6

Same as for Protons: MCz and FZ different!CCE should be interesting!

10Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPP

NEG. SPACE CHARGEAcceptors

POS. SPACE CHARGEDonors

New Wafer Scorecard?• Materials: Neff = Neff0+g*eq

• For p-type: need Neff0 low: high resistivity• For n-type, need Neff0 high: low resistivity

We are analyzing more proton and pion data to verify that donors are produced in p MCzFZ and Mcz data verified for neutron irradiation:Radiation damage in MCz different for protons and neutron irradiation?

-1.00

-0.50

0.00

0.50

1.00

1.50

2.00

2.50

FZ-p,n DOFZ-p,n MCz - n? MCz - p EpiSi-p,n

gc [

10-2

cm

-1]

24 GeV Protons

reactor neutrons

11Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPPAnnealing of p-type FZ and DOFZ sensors (n irradiated)

Annealing of Micron Detectors (neutrons, 500V Bias)

0

2000

4000

6000

8000

10000

12000

14000

16000

1 10 100 1000 10000

Anneal time (min)

Med Q

@500V

(e-)

N-on-P FZ (Micron) Φ=5e14 neutron 2551-7-9N-on-N MCz (Micron) Φ=1e15 neutron 2553-11-11N-on-P FZ (Micron) Φ=1e15 neutron 2551-7-11N-on-P MCz (Micron) 1e15 neutron 2552-7-11N-on-P MCz (Micron) Φ=5e14 neutron 2552-7-9

12Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPPCCE vs. Annealing (n irradiated)

At sLHC fluences for p-type sensors, the entire annealing process is much less pronounced. than for n type FZ.It opens the possibility that sensors need to be cooled only during operations to control the leakage current, but not during beam-off time to prevent anti-annealing

Annealing of Micron Detectors: 800V

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

1 10 100 1000 10000

Anneal time (min)

Med

Q @

80

0V

(e-)

N-on-P FZ (Micron) F =5e14 neutron 2551-7-9N-on-N MCz (Micron) F =1e15 neutron 2553-11-11N-on-P FZ (Micron) F =1e15 neutron 2551-7-11N-on-P MCz (Micron) 1e15 neutron 2552-7-11(p-on- n MCz1.7e 15 neutron)SMART 176-7

13Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPPCCE in neutron Irradiated SSD

Bias Voltage 800V

0

5000

10000

15000

20000

25000

0.0E+00 5.0E+14 1.0E+15 1.5E+15 2.0E+15 2.5E+15 3.0E+15

Fluence [neq/cm2]

Me

dia

n Q

[e-

]n-on-p FZ 2551-7n-on-p FZ 1000 min annn-on-n MCz 2553-11n-on-n MCz 1000min annp-on-n MCz 176-7p-on-n MCz 1000 min annn-on-p Mcz 2552-7n-on-p Mcz 1000min p-on-n Epi SMARTp-on-n MCz SMARTn-on-p Fz SMART

SMART data from A. Messineo (Pisa), Epi(150um) at ~ 300V

14Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPPCharge Collection in Irradiated SSD

Bias Voltage 800V

0

5000

10000

15000

20000

25000

0.0E+00 5.0E+14 1.0E+15 1.5E+15 2.0E+15 2.5E+15 3.0E+15

Fluence [neq/cm2]

Me

dia

n

Q [

e-]

n-on-p FZ 2551-7n-on-p FZ 1000 min annn-on-n MCz 2553-11n-on-n MCz 1000min annp-on-n MCz 176-7p-on-n MCz 1000 min annn-on-p Mcz 2552-7n-on-p Mcz 1000min p-on-n Epi SMARTp-on-n MCz SMARTn-on-p Fz SMARTCassecassecasse protons

P-on-n MCz and FZ strip sensors not sufficiently radiation-hard for the sLHCP-on-n Epi (150 m) is better alternative

15Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPP

Peak and Median Q @ 800V

0

5000

10000

15000

20000

25000

1.E+14 1.E+15 1.E+16

Fluence [neq/cm2]

Co

llec

ted

Ch

arg

e Q

[e-

]

SCIPP n-on-p FZ 2551-7 n irr (prel

SCIPP n-on-p FZ n irr 1000 min ann (prel

Casse NIM A n-on-p FZ p irr

SCIPP n-on-n MCz 2553-11 n irr (prel

SCIPP n-on-n MCz n irr 1000min ann (prel

SCIPP p-on-n MCz 176-7 n irr (prel

SCIPP p-on-n MCz n irr 1000 min ann. (prel

.Casse IEEE 07n-on-p FZ n irr

SCIPP: Binary, Median, StripsCasse: Analog, Peak, Strips

N-on-p strip sensors are sufficiently radiation-hard for the sLHC

Charge Collection in Irradiated SSD

p-on-n Mcz

Long StripsS/N > 10

Short StripsS/N > 10 n-on-p FZ

16Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPP

N-on-p strip sensors are sufficiently radiation-hard for the sLHC ?

Charge Collection in Upgrade Strips ATLAS bias voltage is constraint to < 500V (cables!).

Peak and Median Q @ 500V

0

5000

10000

15000

20000

25000

1.E+14 1.E+15 1.E+16

Fluence [neq/cm2]

Co

llec

ted

Ch

arg

e Q

[e-

]SCIPP n-on-p FZ 2551-7 n irr (prel

SCIPP n-on-p FZ n irr annealed (prel

Casse n-on-p FZ n-irr. IEEE07

Ljubljana n-on-p FZ pad 2551-7 n irr (prel

Ljubljana n-on-p Mcz pad 2552-7 n irr(prel

Casse NIM A n-on-p FZ p irr

SCIPP n-on-n MCz 2553-11 n irr (prel

SCIPP n-on-n MCz n irr ann. 80 min (prel

SCIPP n-on-n MCz n irr ann. 1000 min (prel

.Casse IEEE 07n-onp nirrLong StripsS/N = 10

Short StripsS/N = 10

SCIPP: Binary, Median, StripsCasse: Analog, Peak, StripsLjubljana: Analog, Peak, Pads

17Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPP

0

5000

10000

15000

20000

25000

0

0.2

0.4

0.6

0.8

1

1.2

0 200 400 600 800 1000

Median Pulse Height vs. Efficiency(n-on-p FZ, 5e14 n)

D

G

B

E

Bias Voltage [V]

Pre-rad

5e14 n

Efficiency Median Q Fluence

Long strips efficient at 1fC threshold

Efficiency vs. Collected Charge

• For tracking sensors with binary readout, the figure of merit is not the collected charge, but the efficiency.

• 100% efficiency is reached at a signal-to-noise ratio of S/N ≈ 10, S/Thr > 2

• For long strips (5e14 cm-2) with a signal of about 14ke, the usual threshold of 1fC = 6400 e can be used.

18Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPP

0

5000

10000

15000

20000

25000

0

0.2

0.4

0.6

0.8

1

1.2

0 200 400 600 800 1000

Median Pulse Height vs. Efficiency(n-on-p FZ, 1e15 n)

D

J

B

H

Med

ian

Cha

rge

Col

lect

ed [e

-]

Efficien

cy at 1

fC T

hreshold

Bias Voltage [V]

Pre-rad

1e15 n

Efficiency Median Q Fluence

Short strips efficient if threshold can be lowered

Efficiency vs. Collected Charge

• For short strips (1e15 cm-

2) with a signal of about 8ke, the efficiency at 500V is only 70%.

• The threshold needs to be reduced to about 4500 e, i.e. electronics must be designed for a noise of ~700e.

19Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPP

Much progress with p-type sensors, both in production and understanding

Difference between proton/pion and neutron radiation damage in MCz.P-type: FZ seems to be more predictable than MCz.Good annealing behavior for CCE in p-typeN-on-n has good CCE.

Long strips will work with 1 fC threshold at 500V (ATLAS).Short strips need lowered threshold at 500V (ATLAS).

Conclusions

20Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008

SCIPPSCIPP

Thanks to

RD50 collaborators in Ljubljana, Louvain, CERN, Karlsruhe, PSI, UCSC for carrying out the irradiations.

Collaboration with SMART, Liverpool, Ljubljana.

Acknowledgments