S C IP P
Charge Collection
in p-type Si Tracking Detectors
1) LHC Upgrade environment
2) C-V and CCE after Proton/Pion Irradiation
3) Annealing after neutron irradiation
4) Bias Dependence of collected charge
5) Efficiency
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
SCIPP,
1156 High St
St., Santa Cruz
Cruz, CA 95060
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
1
Fluence in Proposed sATLAS Tracker
Long
Strips
sATLAS Fluences for 3000fb-1
1.E+17
All: RTF Formula
n ((5cm poly)
p y)
pion
proton
2
1.E+16
Fluence
e neq/cm
Radial
Distribution
of Sensors
determined by
Occupancy
< 2%
S C IP P
5 - 10 x LHC
Fl ence
Fluence
Mix of n, p, π
depending on
radius R
1.E+15
1.E+14
1.E+13
Short
Strips
1.E+12
0
Pixels
20
40
60
80
100
120
Radius R [cm]
Strips damage
largely due to
neutrons
ATLAS Radiation Taskforce http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/RADIATION/RadiationTF
p
_document.html
Design fluences for sensors (includes 2x safety factor) :
Innermost Pixel Layer:
O t t Pixel
Outert
Pi l Layers:
L
Short strips:
Long strips:
1*1016 neq/cm2
3*1015 neq/cm
/ 2
1*1015 neq/cm2
4*1014 neq/cm2
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
Pixels Damage due
to neutrons+pions:
need high fluence
proton irradiations
2
RD50 Test Sensors
4” :
Micron
CNM
S C IP P
IRST
RD50 Common Micron (6”)
ATLAS Upgrade HPK (6”)
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
3
RD50 MICRON 6” project
S C IP P
•36
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:
St
i ATLAS strips
i geometry 80 μm
μ pitch
i h ((w/p~1/3)
/ 1/3)
Pads: 5 x 5 mm2 , multiple guard rings
MCz (n-p)
V(FD) [V]
MCz(n-n), (p-n)
520
Fz (n-p)
220
Fz (n-n), (p-n)
75
95
Resitivity
1.9 kΩcm
1.4 kΩcm
13 kΩcm
3.3 kΩcm
Orientation
<100>
<100>
<100>
<100>
Neutron and Proton and Pion (Aug. ’07 ) irradiation of SSD and Diodes
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
4
Charge collection CCE in p-type MCz
after
a
te Proton
oto Irradiation
ad at o
S C IP P
MedQ vs. Bias
3.5
3
Med Q [fC]
M
2.5
2
1.5
1
2552-6-9-1 n-on-p
Mcz 1.3e14
05
0.5
2552-7-13 N-on-P MCz
(Micron) Pre-rad
0
0
200
400
600
800
1000
Bi
Bias
Voltage
V lt
Curious: large loss of charge at small fluence
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
5
Bias Dependence of Efficiency, CCE, Singles
S C IP P
Proton Irradiation 1.3e14
M edQ
3
2 .5
eff @ 1fC
2
1.2
1 .5
Median Charge
1
1
0.8
0 .5
0.6
0
0
100
200
300
400
500
Efficiency
y @ 1 fC
0.4
0.2
0
0
100
200
300
400
500
Count Rate @ 1 fC
Saturation:
Efficiency before Median pulse height
Median pulse height = Single rate
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
6
C-V and CCE in MCz (Protons 1.3e14)
S C IP P
CV comparison
C-V taken at -20oC and 450Hz
0.014
0.012
1/C overestimates the
depletion voltage
0.008
0.006
0.004
C/1
MedQ norm
0.002
0
0
50
100
150
200
250
300
350
400
SMART p-on-n FZ 187
Bias Voltage [V]
Agreement between
low T– Low f 1/C-V and CCE
less perfect than seen before
in n-type FZ
M K Petterson
M.K.
P tt
ett al.,
l NIMA 583,
583 189 (2007)
3.5
Collected Cha
arge [fC]
1/C [1/pF]
1
0.01
3.0
2.5
20
2.0
1.5
1/C 10kHz;+ 22°C
1/C 10kHz; -11°C
1/C 400Hz; -11°C
Charge median value
1.0
0.5
00
0.0
0
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
200
400
600
Voltage [V]
800
7
Protons & P-type: Compare FZ and MCz
S C IP P
p FZ: proton
p
irradiation
8.E-04
1/C^2 [1/pF
F^2]
6.E-04
p-type FZ:
Monotonic Increase in Full Depletion Voltage:
Monotonic Introduction of Acceptors
Material becomes more p-type
Introduction rate not constant? Donor removal?
4.E-04
2.E-04
pre-rad
1e14 proton
3 14 proton
3e14
t
0.E+00
0
100
200
300
400
Bias Voltage [V]
500
600
700
p MCz proton irradiation
2 0E-04
2.0E-04
p-type MCz
1/C^2 [1/pF
F^2]
1.5E-04
Non-Monotonic Increase in depletion
p
voltage:
g
Introduction of Donors
Material becomes initially more n-type:
Type inversion?
Large initial donor introduction rate
1.0E-04
5.0E-05
pre-rad
1e14 proton
4e14 proton
0.0E+00
0
100
200
300
400
Bias Voltage [V]
500
600
700
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
8
Pions & P-type: Compare FZ and MCz
S C IP P
Micron: 1e14 Pion Irradiated SSD
0.0008
0 0007
0.0007
0.0006
1/C [1/pF
F]
0.0005
0.0004
0.0003
0.0002
pre rad 3-1
pre-rad
3 1 2551-2
2551 2
0.0001
p FZ 1e14 3-1 2551-2
p MCz pre-rad 2552-6
n-p MCz 1e14 3-4 2552-6
0
0
100
200
300
400
500
600
700
Bias Voltage [V]
Same as for Protons: MCz and FZ different!
CCE should
h ld be
b interesting!
i t
ti !
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
9
New Wafer Scorecard?
S C IP P
•
Materials: Neff = Neff0+g*Φeq
•
•
For p-type: need Neff0 low: high resistivity
For n-type, need Neff0 high: low resistivity
2.50
24 GeV Protons
reactor neutrons
2.00
NEG.
SPACE
CHARGE
Acceptors
gc [[10-2 cm-1]
1.50
1.00
0 50
0.50
0.00
FZ-p,n
-0.50
-1.00
DOFZ-p,n
MCz - n?
MCz - p
EpiSi-p,n
POS.
SPACE
S
CE
CHARGE
Donors
We are analyzing
g more proton and pion data to verify that donors are produced in p MCz
FZ and Mcz data verified for neutron irradiation:
Radiation damage in MCz different for protons and neutron irradiation?
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
10
Annealing of p-type FZ and DOFZ sensors
S C IP P
(n irradiated)
Annealing of Micron Detectors (neutrons, 500V Bias)
16000
14000
Med Q @500V (e-)
12000
10000
8000
6000
4000
N-on-P
N
on P FZ (Micron) Φ=5e14
Φ 5e14 neutron 2551-7-9
2551 7 9
N-on-N MCz (Micron) Φ=1e15 neutron 2553-11-11
N-on-P FZ (Micron) Φ=1e15 neutron 2551-7-11
N-on-P MCz (Micron) 1e15 neutron 2552-7-11
N-on-P MCz (Micron) Φ=5e14 neutron 2552-7-9
2000
0
1
10
100
1000
10000
Anneal time (min)
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
11
CCE vs. Annealing (n irradiated)
S C IP P
Annealing of Micron Detectors: 800V
18000
16000
Med Q @800V
V (e-)
14000
12000
10000
8000
6000
N-on-P FZ (Micron) F =5e14 neutron 2551-7-9
N-on-N MCz (Micron) F =1e15 neutron 2553-11-11
N-on-P FZ (Micron) F =1e15 neutron 2551-7-11
N-on-P MCz (Micron) 1e15 neutron 2552-7-11
)
)p-on-n
MC 1.7e15
MCz
1 7 15 neutron
t
(SMART 176-7
176 7
4000
2000
0
1
10
100
1000
10000
Anneal time (min)
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
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
12
CCE in neutron Irradiated SSD
n-on-p
n
on p FZ 2551-7
2551 7
n-on-p FZ 1000 min ann
n-on-n MCz 2553-11
n-on-n MCz 1000min ann
p-on-n MCz 176-7
p-on-n MCz
MC 1000 min
i ann
n-on-p Mcz 2552-7
n-on-p Mcz 1000min
p-on-n Epi SMART
p-on-n MCz SMART
n-on-p Fz SMART
25000
Bias Voltage 800V
20000
Median Q [e-]
S C IP P
15000
10000
5000
0
0.0E+00
5.0E+14
1.0E+15
1.5E+15
2.0E+15
2.5E+15
3.0E+15
2
Fluence [neq/cm ]
SMART data from A. Messineo (Pisa), Epi(150um) at ~ 300V
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
13
Charge Collection in Irradiated SSD
n on p FZ 2551
n-on-p
2551-7
7
n-on-p FZ 1000 min ann
n-on-n MCz 2553-11
n-on-n MCz 1000min ann
p-on-n MCz 176-7
p-on-n MCz 1000 min ann
n-on-p Mcz 2552-7
n-on-p
n
on p Mcz 1000min
p-on-n Epi SMART
p-on-n MCz SMART
n-on-p Fz SMART
Casse
casse
casse protons
25000
Bias Voltage 800V
20000
Median Q [e-]
S C IP P
15000
10000
5000
0
0.0E+00
5.0E+14
1.0E+15
1.5E+15
2.0E+15
2.5E+15
3.0E+15
Fluence [neq/cm2]
P-on-n MCz and FZ strip sensors not sufficiently radiation-hard for the sLHC
P-on-n Epi (150 μm) is better alternative
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
14
Charge Collection in Irradiated SSD
Peak and Median Q @ 800V
25000
S C IP P
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
Collected Charg
ge Q [e-]
20000
SCIPP p-on-n MCz n irr 1000 min ann. (prel
Long Strips
S/N > 10
.Casse IEEE07 n-on-p FZ n irr
15000
Short Strips
S/N > 10
n-on-p FZ
10000
5000
SCIPP: Binary, Median, Strips
Casse: Analog, Peak, Strips
p on n Mcz
p-on-n
0
1.E+14
1.E+15
1.E+16
Fluence [neq/cm2]
N-on-p strip sensors are sufficiently radiation-hard for the sLHC
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
15
Charge Collection in Upgrade Strips
S C IP P
ATLAS bias
bi voltage
lt
is
i constraint
t i t to
t < 500V (cables!).
( bl !)
Peak and Median Q @ 500V
SCIPP n-on-p FZ 2551-7 n irr (prel
SCIPP n-on-p FZ n irr annealed (prel
25000
C
Casse
n-on-p FZ n-irr.
i IEEE07
Ljubljana n-on-p FZ pad 2551-7 n irr (prel
Ljubljana n-on-p Mcz pad 2552-7 n irr(prel
Collected
d Charge Q [e-]
Casse NIM A n-on-p FZ p irr
20000
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
MC n irr
i ann. 1000 min
i (prel
(
l
Long Strips
S/N = 10
.Casse IEEE07 n-onp nirr
15000
Short Strips
S/N = 10
10000
5000
SCIPP: Binary
Binary, Median,
Median Strips
Casse: Analog, Peak, Strips
Ljubljana: Analog, Peak, Pads
0
1.E+14
1.E+15
1.E+16
2
Fluence [neq/cm ]
N-on-p strip sensors are sufficiently radiation-hard for the sLHC ?
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
16
Efficiency vs. Collected Charge
• For tracking sensors with
binary readout, the figure
of merit is not the collected
charge,
h
bbutt the
th efficiency.
ffi i
• 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.
Median Pulse Height vs. Efficiency
(n-on-p FZ, 5e14 n)
S C IP P
Efficiency Median Q Fluence
25000
B
D
Pre-rad
E
G
5e14 n
1.2
1
20000
08
0.8
15000
0.6
10000
04
0.4
5000
0.2
0
0
200
400
600
800
0
1000
Bias Voltage [V]
Long strips efficient at 1fC threshold
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
17
Efficiency vs. Collected Charge
Median Pulse Height vs. Efficiency
(n-on-p FZ, 1e15 n)
S C IP P
Efficiency Median Q Fluence
• The threshold needs to be
reduced to about 4500 e,
i.e. electronics must be
designed for a noise of
~700e.
D
Pre-rad
H
J
1e15 n
1.2
1
20000
08
0.8
15000
0.6
10000
04
0.4
5000
0.2
0
0
200
400
600
800
Efficien
ncy at 1 fC T
Threshold
• For short strips (1e15 cm2) with a signal of about
8ke, the efficiency at 500V
is only 70%.
Media
an Charge Co
ollected [e-]
25000
B
0
1000
Bias Voltage [V]
Short strips efficient if threshold can be lowered
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
18
Conclusions
S C IP P
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.
G d annealing
Good
li behavior
b h i for
f CCE in
i p-type
t
N-on-n has good CCE.
Long strips will work with 1 fC threshold at 500V (ATLAS).
(ATLAS)
Short strips need lowered threshold at 500V (ATLAS).
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
19
Acknowledgments
S C IP P
Thanks to
RD50 collaborators in Ljubljana, Louvain, CERN, Karlsruhe, PSI, UCSC for
carrying out the irradiations.
irradiations
Collaboration with SMART, Liverpool, Ljubljana.
Hartmut F.-W. Sadrozinski, Barcelona April 14, 2008
20