Hamburg University:Plans for SLHC Silicon Detector

R&DGeorg Steinbrück

WienFeb 20, 2008

2

Plans for SLHC Silicon Detector R&D

• Projects and collaborations of the group

• Strategies

• Measurements of material properties

• Sensor simulation/optimization

• Simulation of detector performance

3

Projects and Collaborations of the Group

• The group is involved in the following Projects with respect to Detector R&D:

• LHC (funded by BMBF)

• HGF-Alliance (17 German Universities + DESY + FZK) “Physics at the terascale”

• WP1: The Virtual Laboratory for Detector Technologies

• WP2: Detector R&D Projects

• HPAD-XFEL (with Bonn, PSI, DESY)

• Approved. Project started.

• PAD-Marie Curie (with CERN, DESY, …) “Marie Curie Training Network on Particle Detectors”

• Approved in principle. Contract negotiations with EU.

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Strategies

Study of macroscopic properties:

IV, CV, TCT (transient current technique)

Study of microscopic properties: Defects DLTS: deep level transient spectroscopy, TSC: thermally stimulated current method)

Neff, I, e,h :f(Doping, t, radiation dose, …)Sensor simulation/ optimization:

E, I, C as a function of irradiation, material

Simulation of charge collection in detector , spatial resolution, reconstruction

Monte Carlo

•simulation

•experiment: -multi-TCT -testbeam

detector

= dE/dx x sensor x FE electronics

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Examples Material Properties

0 2.1015 4.1015 6.1015 8.1015 1016

eq [cm-2]

0.0

1.0.1014

2.0.1014

3.0.1014

Nef

f(t0)

[cm

-3]

0

100

200

300

400

500

600

Vfd

(t0)

[V

] no

rmal

ized

to 5

0 m

25 m, 80oC25 m, 80oC

50 m, 80oC50 m, 80oC

50 m, 60oC50 m, 60oC

23 GeV protons23 GeV protons

0 2.1015 4.1015 6.1015 8.1015 1016

eq [cm-2]

0

5.1013

1014

Nef

f (t 0

) [cm

-3]

0

50

100

150V

fd (

t 0)[

V]

norm

aliz

ed to

50 m

50 m50 m

25 m25 m

Reactor neutronsReactor neutrons

Ta = 80oCTa = 80oC 0 2.1015 4.1015 6.1015 8.1015 1016

eq [cm-2]

0

50

100

150

200

250

Vfd

[V

]

50 m simulation50 m simulation

50 m after 50 min@80C annealing50 m after 50 min@80C annealing

25 m simulation25 m simulation

25 m after 50 min@80C annealing25 m after 50 min@80C annealing

SLHC operating scenario, measurement compared to simulation: “Hamburg Model”

Thin n-type epi-Silicon. No space charge sign inversion after proton and neutron irradiation.

Explanation: Introduction of shallow donors overcompensates creation of acceptors.

More pronounced in 25µm Si due to higher oxygen concentration.

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rad. induced acceptors in lower half of band

gap: neg. charged, neg. space charge hole traps (H). Increase with annealing time neg. space charge increases, Neff decreases!

conduction band

valence band

1 10 100 1000 10000-5.0x1012

0.0

5.0x1012

1.0x1013

1.5x1013

2.0x1013

2.5x1013

3.0x1013

3.5x1013

MCz Neff at RT Nd - [H116K] - [H140K] - [H152K]

Co

nce

ntr

atio

n (

cm-3)

Annealing time at 800C (minutes)

EPI-DO Neff at RT Nd - [H116K] - [H140K] - [H152K]

EPI-ST N

eff at RT

Nd-[H116K]-[H140K]-H[152K]

Study of Microscopic Defects: Thermally Stimulated Current

(TSC)Neff

0 20 40 60 80 100 120 140 160 180 2000

10

20

30

40

50

60

70

80

90MCz

H(140K)

BD+/++

IO2

-/0

VO

V2+?

H(152K)

H(116K)

BD0/++

E(35K)

E(28K)

H(40K)

TS

C s

igna

l (pA

)

Temperature (K)

Forward injection at 5K, RB=300V as irradiated 20min@80C 80 min@ 80C 320min@80C 1370min@80C 34270min@80C

TSC results for fully depleted diodes.Goal: Identification of defects

responsible for long term annealing(“reverse annealing“) of Neff. VFD

Difference ND-H und Neff: VP

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Simulation of Detector Performance, Comparison with Test Beam Data

Example testbeam measurement for

irradiated CMS sensors

integrated (PH(R)/PH(L)+PH(R)) versus

for various incidence angles.

Example simulation:

Reconstructed position versus reduced incidence position on strip.

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Simulation of Charge Clouds

electron cloudhole cloud

Front

Backside

structure (strip/pixel)

Bias-Voltage Vbias

t2

t2

t1

t1

t0

I1 I0

Current is induced to all strips

Readout of current allows to investigate charge cloud distribution

I0 current on closest strip

I1 current on neighboring strip

black: sum of both strips

e collected

h collected

Goal: Study the effects of trapping.

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Verification with Multi Channel TCT

attenuator + amplifier

Laser

optics

z table

x-y stagetemporary detector support

Goal: Time-resolved measurement of charge collection in Si-pixel and strip detectors in multiple channels up to very high charge densities. fine-grain position and angle scans.

Multi-TCT under construction in Hamburg:

• ps laser (1052 nm and 660 nm), <90ps, Wmax~200pJ, spot size <10 µm (red)

• penetration depth 3 µm (red), 1000µm (IR)

• fast amplifiers (miteq)

• data acquisition with fast oscilloscope (500 MHz, 1GS/channel), possible upgrade to digitizer cards with up to 20 ch, synchronized

• cooled detector support (Peltier)

10 ns

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People

• Doris Eckstein (main Hamburg contact person)

• Robert Klanner

• Peter Schleper

• Georg Steinbrück

• Eckhart Fretwurst (defect engineering)

• Julian Becker, PhD student (multi-TCT)

• Volodymyr Khomenkov (starting ~March) (Detector simulation)

• Ajay Srivastava (just started) (sensor simulation: TCAD,…)

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Backup

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Schematic set-up of the Multi-TCT

optic fiber and optics

working distance

optic axis (z)

z

x

y

laser and driver

Oscilloscopeattenuators and amplifiers

bias voltage supply, leakage and guardring current measurement

PID temperature controller

trigger line

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Laser system (PicoQuant)

660 nm (red)• minimum energy:

1 mip 10 x XFEL /pulse 70 ps pulse width

• maximum energy: 140 pJ/pulse 4x104 XFEL-/pulse 100 million e-h pairs 4000 mips 800 ps pulse width

1052nm (infrared)• minimum energy:

1 mip 10 x XFEL /pulse 70 ps pulse width

• maximum energy: 275 pJ/pulse 4x104 XFEL-/pulse 100 million e-h pairs 4000 mips 700 ps pulse width

Gaussian beam after single mode fiber

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Laser system (red)

maximum energy: 140 pJ/pulse 800 ps pulse width

minimum energy: 22 pJ/pulse 70 ps pulse width

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Laser system (IR)

minimum energy: 44 pJ/pulse 70 ps pulse width

maximum energy: 275 pJ/pulse 700 ps pulse width