First Measurement of Electrical characteristics

of ATLAS07 Series I large detectors

Jan Bohm, Jan Brož, Zdeněk Doležal,Peter Kodyš, Petr Kubík, Marcela Mikeštíková

Charles University in PragueAcademy of Sciences of the Czech Republic

Introduction

Strip detectors in the upgraded ATLAS STC in SLHC will be exposed to anticipated radiation fluence up to 5-9 x 1014 neq/cm2 which will substantively change their properties. Until now, changes of the device properties caused by such radiation are mainly studied by irradiation of miniature sensors. Presently, irradiation of real size sensors by protons is being prepared at CERN PS and by neutrons in Prague - Rez.

The aim of the Prague group is• development of methodic for irradiation of large sensors (10 x 10 cm2)

and whole modules under bias and with cooling by fast neutrons from cyclotron neutron generator in Prague-Rez (reaction of p with D2O)

• verification of this methodic by comparing its results with results of irradiated mini’s in Ljubljana

• comparison of irradiation results achieved in Prague and CERN PS • additional irradiation of sensors at CERN PS to get mixed irradiation more about neutron facilities in Prague in Peter’s talk

214th RD50 Workshop 03-05 June 2009, Marcela Mikeštíková

Full Size Silicon Micro-strip Sensors6 full size HPK ATLAS07-Series I sensors were delivered to Prague second

week of May09 • n-on-p (FZ)• AC-coupled readout• n-strips biased through polysilicon resistors• with “p-stop” isolation (4*1012ions/cm2)• 4 segments: 2 x straight, 2 x stereo angle• pitch 74.5 µm, 1280 strips• size: 10cm x 10 cm, 320 µm

• 2500 p-on-n sensors for SCT ATLAS were evaluated at Prague Si-laboratory in 2001-2002In last 14 days• we prepared new setup for evaluation n-on-p sensors with Automatic Probe Station

PS2S150E made in Karlsruhe• we made a modification of the LabView test software to run with negative bias voltage n-on-

p sensors . • until now we used Vbias up to -600V and we are preparing setup for IV up to -1000 V to see

breakdown voltage

314th RD50 Workshop 03-05 June 2009, Marcela Mikeštíková

Electrical characteristics – Preliminary results

• IV, CV characteristics up to 600 V• Vdepletion• Interstrip Capacitance• Coupling Capacitance• Polysilicon Bias Resistance• Interstrip Resistance• Strip integrity

414th RD50 Workshop 03-05 June 2009, Marcela Mikeštíková

in preparation

IV characteristcsLeakage Current

0.00

50.00

100.00

150.00

200.00

250.00

0 100 200 300 400 500 600

-Vbias [V]

-Ile

ak [

nA

]

w33w32w35w37w38w39

Ileak normalized to 20°CRH =29%

ATLAS07-P-SSSD_Series I

IV curve normalized to 20°Caverage Ileak @ 600 V = 225.1 nA (@20°C)

No breakdown up to 600 V, all 6 sensors very similar 514th RD50 Workshop 03-05 June 2009,

Marcela Mikeštíková

Depletion Voltage

• extracted as crossing of the linear rise and the saturated value• very smooth behavior

Depletion Voltage

196

197

198

199

200

201

202

203

W32 W33 W35 W37 W38 W39

Sensor number

Vd

ep

[V

]

average 200.8 V

ATLAS07-P-SSSD_Series I • maximum difference in Vdep is 3V

614th RD50 Workshop 03-05 June 2009, Marcela Mikeštíková

Depletion Voltage

0.00E+00

2.00E-02

4.00E-02

6.00E-02

8.00E-02

1.00E-01

1.20E-01

0 100 200 300 400 500 600

-Vbias [V]

1/C

2 [n

F-2]

W32 Vdep=202.5

W33 Vdep=202.3

W35 Vdep=201.4

W37 Vdep=198.8

W38 Vdep=200.3

W39 Vdep=199.4

ATLAS07-P-SSSD_Series I

RH=29 % T=25°C

1kHz with CR in Series

Interstrip Capacitance• between a central strip and its nearest neighbour on both sides with others

floating• consistent with measurement of other groups

Interstrip Capacitance

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 100 200 300 400 500 600 700

-Vbias [V]

Cin

t [p

F]

Segment4

Segment3

Segment2

Segment1

ATLAS07-Series I - W32

T=26°C

RH=36%

Average =1.8 pF/strip

100kHz test frequency with CR in parallel

714th RD50 Workshop 03-05 June 2009, Marcela Mikeštíková

•0.8 pF/cm

Coupling Capacitance• between the strip metal and strip implant• up to 10kHz constant, @ 1kHz middle of plateau

814th RD50 Workshop 03-05 June 2009, Marcela Mikeštíková

Frequency dependence of Coupling Capacitance

0

10

20

30

40

50

60

70

80

0 1 10 100 1000

Freq [kHz]

Cc

ou

pl [

pF

]

ATLAS07 Series I - W32 - Segment 2

RH=36%, T=25°C

CR in Parallel

Vbias = 0 V

Coupling Capacitance

• changes in level of 2 pF

914th RD50 Workshop 03-05 June 2009, Marcela Mikeštíková

Coupling Capacitance

67.8

68.0

68.2

68.4

68.6

68.8

69.0

69.2

69.4

69.6

69.8

70.0

1 10 100 1000

- Vbias [V]

Cc

ou

pl [

pF

]

ATLAS07 Series I - W32 - Segment 2

RH=36%, T=25°C

1 kHz test frequency, CR in Parallel

Ccoupl@200V = 68.1 pF

Polysilicon Bias Resistance• Voltage 1-6 V was applied to DC pad. IV for applied voltage was measured on bias rail • Rbias = dVappl ⁄ dI as a function of bias voltage • The backplane on VBIAS, bias rail on GRD

1014th RD50 Workshop 03-05 June 2009, Marcela Mikeštíková

Polysilicon Bias Resistance

1.400

1.405

1.410

1.415

1.420

1.425

1.430

1.435

1.440

0 100 200 300 400 500 600

-Vbias [V]

Rb

ias [

MO

hm

]

ATLAS07-P-SSSD_Series I - W32

Rbias @ 200 V = 1.435MOhm

Next steps Next step before irradiation: • continue with measurements to increase statistics before irradiation• measure the strip integrity with automatic probe station • prepare setup for IV up to 1000 V to see breakdown voltage• measure the effect of the cable lenghs for online measurements during irradiation and sensor

temperature on electrical characteristics Irradiation plan:• irradiation of 4 full size sensors with fast neutrons at Cyclotron U-120M at NPI Rez in Prague at 3 different

distances from the target to get different fluences. • we have estimated that the full size detectors could be irradiated up to integrated fluency 1.3*1015neq/cm2

in ≈50 hours with non-homogenities ≈20% • calibration irradiation run: June 26-28, 2009 to get ~0.5*1015neq/cm2

• next run is planned in October 09 giving possibility to irradiate sensors with FE or complete modules (if any) up to 1.3*1015neq/cm2

We are preparing irradiation setup • with cooling (liquid N) up to -25 or -30° C • with on-line monitoring of IV, CV of all irradiated sensors, • with on-line measurement of Cinterstrip, Rbias, Rinterstrip, Ccoupl at 3 strips of one sensor during irradiation (contact

to 3 adjacent AC pads, 3 adjacent DC pads, bias pad and backplane) After irradiation:• perform measurements of sensors at -25°C before and after controlled beneficial annealing to check

functionality of full size sensors after irradiation up to fluence in the upgraded SCT in the SLHC • evaluate irradiated sensors with non-irradiated DAQ

1114th RD50 Workshop 03-05 June 2009, Marcela Mikeštíková

Summary• we prepared setup for evaluation of large n-on-p sensors (10x10cm) • we changed LabView test software• result of measurement of IV, CV, Cint, Ccoupl, Rbias are consistent with measurements of

others on the same type of sensors• Rint – different methods of measurement are still tested • strip integrity will be prepared in the next week• we prepare methodic for irradiation of large sensors (10 x 10 cm2) and whole modules under

bias and with cooling by fast neutrons from cyclotron neutron generator in Prague-Rez D2O(p,xn)

1214th RD50 Workshop 03-05 June 2009, Marcela Mikeštíková