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11 th ICATPP Conference on Astroparticle, Particle, Space Physics, Detectors and Medical Physics Applications Villa Olmo, Como (Ialy) 5-9 October 2009. Recent advances in the development of radiation tolerant silicon detectors for the Super - LHC.

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michael moll cern ph on behalf of the rd50 collaboration http www cern ch rd50

11th ICATPP Conference onAstroparticle, Particle, Space Physics,Detectors and Medical Physics ApplicationsVilla Olmo, Como (Ialy) 5-9 October 2009

Recent advances in the development of radiation tolerant silicon detectors for the Super - LHC

Michael Moll (CERN/PH)on behalf of the RD50 collaborationhttp://www.cern.ch/rd50

- A review on recent RD50 results -

slide2

RD50 - Development of Radiation Hard Semiconductor Devices for High Luminosity Colliders

247 Members from 47 Institutes

RD50

38 European institutesBelarus (Minsk), Belgium (Louvain), Czech Republic (Prague (3x)), Finland (Helsinki, Lappeenranta), Germany (Dortmund, Erfurt, Freiburg, Hamburg, Karlsruhe, Munich), Italy (Bari, Florence, Padova, Perugia, Pisa, Trento), Lithuania (Vilnius), Netherlands (NIKHEF), Norway (Oslo (2x)), Poland (Warsaw(2x)), Romania (Bucharest (2x)),Russia (Moscow, St.Petersburg), Slovenia (Ljubljana), Spain (Barcelona, Valencia), Switzerland (CERN, PSI), Ukraine (Kiev), UnitedKingdom (Glasgow, Lancaster, Liverpool)

8 North-American institutesCanada (Montreal), USA (BNL, Fermilab, New Mexico, Purdue, Rochester, Santa Cruz, Syracuse)

1 Middle East instituteIsrael (Tel Aviv)

Detailed member list: http://cern.ch/rd50

RD50: Nov.2001 collaboration formed ; June 2002 approved by CERN

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -2-

outline
Outline

Motivation to develop radiation harder detectors

Super-LHC and expected radiation levels at the Super-LHC

Radiation induced degradation of detector performance

Radiation Damage in Silicon Detectors

Macroscopic damage (changes in detector properties)

Microscopic damage (crystal damage)

Approaches to obtain radiation hard sensors

Material Engineering

Silicon materials – FZ, MCZ, DOFZ, EPI

Other semiconductors

Device Engineering

p-in-n, n-in-n and n-in-p sensors

3D sensors and thin devices

Sensors for sLHC and some very recent results

Collected Charge – Signal to Noise

Mixed irradiations

Summary

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -3-

future plans towards slhc
Future Plans: Towards sLHC

New injectors + IR upgrade phase 2

Linac4 + IR upgrade phase 1

Collimation phase 2

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -4-

future plans towards slhc1
Future Plans: Towards sLHC

Phase II upgrades: CMS: Tracker replacement

ATLAS: New ‘all silicon’ tracker4 pixel, 3 short & 2 long strip layers ( 3.5 cm to 95 cm)

Phase I upgrades:CMS: New Pixel Detector

(4 layers 4-16 cm + 6 disc)

ATLAS: IBL – Insertable b-layer (add layer at 3.5 cm)

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -5-

slide6

5 years

10 years

2500 fb-1

500 fb-1

Radiation levels at sLHC (ATLAS, CMS)

  • SLHC (Phase II upgrades)LHC (2009 ?) L = 1034cm-2s-1f(r=4cm) ~3·1015cm-2
  • Super-LHC (2018 ?) L = 1035cm-2s-1f(r=4cm) ~1.6·1016cm-2

 5

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -6-

signal degradation for lhc silicon sensors
Signal degradation for LHC Silicon Sensors

Note: Measured partly under different conditions! Lines to guide the eye (no modeling)!

Pixel sensors: max. cumulated fluence for LHC

Strip sensors: max. cumulated fluence for LHC

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -7-

signal degradation for lhc silicon sensors1
Signal degradation for LHC Silicon Sensors

Note: Measured partly under different conditions! Lines to guide the eye (no modeling)!

Pixel sensors: max. cumulated fluence for LHC andSLHC

SLHC will need more radiation tolerant tracking detector concepts!Boundary conditions & other challenges:Granularity, Powering, Cooling, Connectivity,Triggering, Low mass, Low cost!

Strip sensors: max. cumulated fluence for LHC andSLHC

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -8-

outline1
Outline

Motivation to develop radiation harder detectors

Super-LHC and expected radiation levels at the Super-LHC

Radiation induced degradation of detector performance

Radiation Damage in Silicon Detectors

Macroscopic damage (changes in detector properties)

Microscopic damage (crystal damage)

Approaches to obtain radiation hard sensors

Material Engineering

Silicon materials – FZ, MCZ, DOFZ, EPI

Other semiconductors

Device Engineering

p-in-n, n-in-n and n-in-p sensors

3D sensors and thin devices

Sensors for sLHC and some very recent results

Collected Charge – Signal to Noise

Mixed irradiations

Summary

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -9-

summary radiation damage in silicon sensors
Summary: Radiation Damage in Silicon Sensors

Influenced by impuritiesin Si – Defect Engineeringis possible!

Same for all tested Silicon materials!

Can be optimized!

  • Two general types of radiation damage to the detector materials:

Bulk (Crystal) damagedue to Non Ionizing Energy Loss (NIEL) - displacement damage, built up of crystal defects –

    • Change of effective doping concentration (higher depletion voltage, under- depletion)
    • Increase of leakage current (increase of shot noise, thermal runaway)
    • Increase of charge carrier trapping (loss of charge)

Surface damagedue to Ionizing Energy Loss (IEL) - accumulation of positive in the oxide (SiO2) and the Si/SiO2 interface –affects: interstrip capacitance (noise factor), breakdown behavior, …

  • Impact on detector performance and Charge Collection Efficiency (depending on detector type and geometry and readout electronics!)Signal/noise ratio is the quantity to watch

 Sensors can fail from radiation damage !

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -10-

macroscopic effects depletion voltage
Macroscopic Effects – Depletion Voltage

…. with time (annealing):

• Short term: “Beneficial annealing”• Long term: “Reverse annealing” - time constant depends on temperature:~ 500 years (-10°C)~ 500 days ( 20°C)~ 21 hours ( 60°C) - Consequence: Detectors must be cooled even when the experiment is not running!

before inversion

p+

n+

n+

p+

after inversion

  • Change of Depletion Voltage Vdep (Neff)…. with particle fluence:

•“Type inversion”: Neff changes from positive to negative (Space Charge Sign Inversion)

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -11-

impact of defects on detector properties
Impact of Defects on Detector Properties

Shockley-Read-Hall statistics

charged defects Neff , Vdepe.g. donors in upper and acceptors in lower half of band gap

Trapping (e and h) CCEshallow defects do not contribute at room temperature due to fast detrapping

generation leakage currentLevels close to midgap most effective

Impact on detector properties can be calculated if all defect parameters are known:n,p : cross sections E : ionization energy Nt : concentration

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -12-

defect characterization methods
Defect Characterization - Methods

TSC (Thermally Stimulated Currents)

Methods used by RD50 Collaboration (RD50-WODEAN project):

  • C-DLTS (Capacitance Deep Level Transient Spectroscopy)
  • I-DLTS(Current Deep Level Transient Spectroscopy)
  • TSC(Thermally Stimulated Currents)
  • PITS (Photo Induced Transient Spectroscopy)
  • FTIR (Fourier Transform Infrared Spectroscopy)
  • RL (Recombination Lifetime Measurements)
  • PC (Photo Conductivity Measurements)
  • PL (Photo Luminescence)
  • EPR (Electron Paramagnetic Resonance)
  • TCT (Transient Charge Technique)
  • CV/IV(Capacitance Voltage and Current Voltage Characteristics)Further interesting methods:
  • Positron Annihilation, TEM, TSCAP, …..

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -13-

summary defects with strong impact on the device properties at operating temperature
Summary – defects with strong impact on the device properties at operating temperature

Point defects

EiBD = Ec – 0.225 eV

nBD =2.310-14 cm2

EiI = Ec – 0.545 eV

nI =2.310-14 cm2

pI =2.310-14 cm2

Cluster related centers

Ei116K = Ev + 0.33eV

p116K =410-14 cm2

Ei140K = Ev + 0.36eV

p140K =2.510-15 cm2

Ei152K = Ev + 0.42eV

p152K =2.310-14 cm2

Ei30K = Ec - 0.1eV

n30K =2.310-14 cm2

0 charged at RT

+/- charged at RT

E30K 0/+

P0/+

VO -/0

BD 0/++

V2 -/0

Ip0/-

H152K 0/-

H140K0/-

H116K0/-

CiOi+/0

B 0/-

extended defects

Point defects

positive charge (higher introduction after proton irradiation than after neutron irradiation)

positive charge (high concentration in oxygen rich material)

leakage current+ neg. charge(current after  irradiation)

Reverse annealing(neg. charge)

I.Pintilie, NSS, October 2008, Dresden

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -14-

correlation microscopic and macroscopic data
Correlation: Microscopic and Macroscopic data
  • TSC and CV measurements (Isothermal annealing after 2.3x1014 cm-2 – 23GeV protons)

[I.Pintilie et al., “Radiation Induced Point and Cluster-Related Defects with Strong Impact to Damage Properties of Silicon Detectors”, to be published in Nucl. Instr. and Meth. A]

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -15-

correlation microscopic and macroscopic data1
Correlation: Microscopic and Macroscopic data
  • TSC and CV measurements (Isothermal annealing after 2.3x1014 cm-2 – 23GeV protons)

Acceptors – negative space charge

Donors – positive space charge

  • Microscopic measurements predict macroscopic results

[I.Pintilie et al., “Radiation Induced Point and Cluster-Related Defects with Strong Impact to Damage Properties of Silicon Detectors”, to be published in Nucl. Instr. and Meth. A]

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -16-

outline2
Outline

Motivation to develop radiation harder detectors

Super-LHC and expected radiation levels at the Super-LHC

Radiation induced degradation of detector performance

Radiation Damage in Silicon Detectors

Macroscopic damage (changes in detector properties)

Microscopic damage (crystal damage)

Approaches to obtain radiation hard sensors

Material Engineering

Silicon materials – FZ, MCZ, DOFZ, EPI

Other semiconductors

Device Engineering

p-in-n, n-in-n and n-in-p sensors

3D sensors and thin devices

Sensors for sLHC and some very recent results

Collected Charge – Signal to Noise

Mixed irradiations

Summary

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -17-

silicon growth processes
Silicon Growth Processes

Floating Zone Silicon (FZ)

  • Czochralski Silicon (CZ)
  • The growth method used by the IC industry.
  • Difficult to producevery high resistivity

Poly silicon

RF Heating coil

Single crystal silicon

Czochralski Growth

Float Zone Growth

  • Epitaxial Silicon (EPI)
  • Basically all silicon tracking detectors made out of FZ silicon
  • Some pixel sensors out of DOFZDiffusion Oxygenated FZ silicon
  • Chemical-Vapor Deposition (CVD) of Si
  • up to 150 mm thick layers produced
  • growth rate about 1mm/min

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -18-

slide19

standardfor particledetectors

used for LHC Pixel detectors

“new”siliconmaterial

Silicon Materials under Investigation by RD50

  • DOFZ silicon- Enriched with oxygen on wafer level, inhomogeneous distribution of oxygen
  • CZ/MCZ silicon- high Oi (oxygen) and O2i (oxygen dimer) concentration (homogeneous) - formation of shallow Thermal Donors possible
  • Epi silicon- high Oi , O2i content due to out-diffusion from the CZ substrate (inhomogeneous) - thin layers: high doping possible (low starting resistivity)
  • Epi-Do silicon - as EPI, however additional Oi diffused reaching homogeneous Oi content

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -19-

slide20

FZ, DOFZ, Cz and MCz Silicon

24 GeV/c proton irradiation (n-type silicon)

  • Strong differences in Vdep
    • Standard FZ silicon
    • Oxygenated FZ (DOFZ)
    • CZ siliconand MCZ silicon
  • Strong differences in internal electric field shape(space charge sign inversion, no inversion, double junction effects,…)
  • Common to all materials (after hadron irradiation, not after  irradiation):
    • reverse current increase
    • increase of trapping (electrons and holes) within ~ 20%

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -20-

correlation microscopic and macroscopic data2
Correlation: Microscopic and Macroscopic data
  • Epitaxial silicon irradiated with 23 GeV protons vs reactor neutrons

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -21-

[A.Junkes, Hamburg University, RD50 Workshop June 2009]

mixed irradiations change of n eff
Mixed irradiations – Change of Neff
  • Exposure of FZ & MCZ silicon sensors to ‘mixed’ irradiations
    • First step: Irradiation with protons or pions
    • Second step: Irradiation with neutrons

FZ (low oxygen): Accumulation of damage

MCZ (high oxygen content): Compensation of damage

[G.Kramberger et al., “Performance of silicon pad detectors after mixed irradiations with neutrons and fast charged hadrons”, Nucl. Instr. and Meth. A, article in press. (doi:10.1016/j.nima.2009.08.030)]

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -22-

slide23

Use of other semiconductor materials?

  • Diamond: wider bandgap  lower leakage current less cooling needed
  • Signal produced by m.i.p: Diamond 36 e/mm Si 89 e/mm Si gives more charge than diamond
  • GaAs, SiC and GaN  strong radiation damage observed no potential material for sLHC detectors
  • Diamond (RD42)  good radiation tolerance (see later) already used in LHC beam condition monitoring systems considered as potential detector material for sLHC pixel sensors

poly-CVD Diamond –16 chip ATLAS pixel module

single crystal CVD Diamond of few cm2

see presentation of Harris Kagan (Wednesday 14:30)

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -23-

outline3
Outline

Motivation to develop radiation harder detectors

Super-LHC and expected radiation levels at the Super-LHC

Radiation induced degradation of detector performance

Radiation Damage in Silicon Detectors

Macroscopic damage (changes in detector properties)

Microscopic damage (crystal damage)

Approaches to obtain radiation hard sensors

Material Engineering

Silicon materials – FZ, MCZ, DOFZ, EPI

Other semiconductors

Device Engineering

p-in-n, n-in-n and n-in-p sensors

3D sensors and thin devices

Sensors for sLHC and some very recent results

Collected Charge – Signal to Noise

Mixed irradiations

Summary

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -24-

advantage of non inverting material p in n detectors schematic figures
Advantage of non-inverting materialp-in-n detectors (schematic figures!)

Fully depleted detector(non – irradiated):

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -25-

advantage of non inverting material p in n detectors schematic figures1
Advantage of non-inverting materialp-in-n detectors (schematic figures!)

non inverted

  • non-inverted, under-depleted:
  • Limited loss in CCE
  • Less degradation with under-depletion

Fully depleted detector(non – irradiated):

Be careful, this is a very schematic explanation, reality is more complex !

heavy irradiation

inverted

  • inverted to “p-type”, under-depleted:
  • Charge spread – degraded resolution
  • Charge loss – reduced CCE

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -26-

reverse annealing in non inverting n type silicon
Reverse annealing in non-inverting n-type silicon

Example: 50 mm thick silicon detectors:- Epitaxial silicon (50Wcm) and Thin FZ silicon (4KWcm)

inverted

not inverted

  • FZ silicon: Type inverted, increase of depletion voltage with time
  • Epitaxial silicon: No type inversion, decrease of depletion voltage with time No need for low temperature during maintenance of SLHC detectors!

[E.Fretwurst et al.,RESMDD - October 2004]

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -27-

device engineering p in n versus n in p detectors
Device engineeringp-in-n versus n-in-p detectors

p-type silicon after high fluences:(still p-type)

n-type silicon after high fluences:(type inverted)

n+on-p

p+on-n

  • n-on-p silicon, under-depleted:
  • Limited loss in CCE
  • Less degradation with under-depletion
  • Collect electrons (3 x faster than holes)
  • p-on-n silicon, under-depleted:
  • Charge spread – degraded resolution
  • Charge loss – reduced CCE

Comment:- Instead of n-on-p also n-on-n devices could be used

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -28-

reality complex double junctions
Reality: Complex double junctions

p-type silicon after high fluences:(still “p-type”)

  • Dominant junction close to n+ readout strip for FZ n-in-p
  • For MCZ p-in-n even more complex fields have been reported:
    • no “type inversion”(SCSI) = dominant field remains at p implant
    • “equal double junctions” with almost symmetrical fields on both sides

n+on-p

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -29-

fz n in p microstrip detectors n p p irrad
FZ n-in-p microstrip detectors (n, p, p - irrad)

n-in-p microstrip p-type FZ detectors(Micron, 280 or 300mm thick, 80mm pitch, 18mm implant )

Detectors read-out with 40MHz(SCT 128A)

[A.Affolder, Liverpool, RD50 Workshop, June 2009]

Signal(103 electrons)

800V

Fluence(1014 neq/cm2)

500V

  • CCE: ~7300e (~30%) after ~ 11016cm-2 800V
  • n-in-p sensors are strongly considered for ATLAS upgrade(previously p-in-n used)

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -30-

fz n in p microstrip detectors n p p irrad1
FZ n-in-p microstrip detectors (n, p, p - irrad)

n-in-p microstrip p-type FZ detectors(Micron, 280 or 300mm thick, 80mm pitch, 18mm implant )

Detectors read-out with 40MHz(SCT 128A)

[A.Affolder, Liverpool, RD50 Workshop, June 2009]

Signal(103 electrons)

Fluence(1014 neq/cm2)

  • CCE: ~7300e (~30%) after ~ 11016cm-2 800V
  • n-in-p sensors are strongly considered for ATLAS upgrade(previously p-in-n used)
  • no reverse annealing in CCE measurementsfor neutron and proton irradiated detectors

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -31-

slide32

n-columns

p-columns

wafer surface

PLANAR

3D

p+

p+

p+

n+

50 mm

-

300 mm

n-type substrate

-

-

-

-

-

-

-

-

-

+

+

+

+

+

+

+

+

+

+

3D detector - concept

  • “3D” electrodes: - narrow columns along detector thickness, - diameter: 10mm, distance: 50 - 100mm
  • Lateral depletion: - lower depletion voltage needed - thicker detectors possible - fast signal - radiation hard

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -32-

slide33

Example: Testbeam of 3D-DDTC

  • DDTC – Double sided double type column

see presentation of Michael Koehler (Wednesday 16:30 – Tracker III)

[G.Fleta, RD50 Workshop, June 2007]

  • Testbeam data – Example: efficiency map[M.Koehler, Freiburg Uni, RD50 Workshop June 09]
  • Processing of 3D sensors is challenging,but many good devices with reasonableproduction yield produced.
  • Competing e.g. for ATLAS IBL pixel sensors

40V applied~98% efficiency

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -33-

outline4
Outline
  • Silicon Tracking Detectors at LHC
  • Motivation to study radiation hardness
  • Radiation Damage in Silicon Detectors
  • Approaches to obtain radiation hard sensors
  • Silicon Sensors for the LHC upgrade
    • A comparison of technologies in terms of collected charge (signal)Comment:The collected charge is a crucial parameter, but there are other important parameters to be considered: Signal to Noise ratio, efficiency, system aspects, availability and price of technology, reliability, cooling, track resolution, ….)
  • Summary

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -34-

silicon materials for tracking sensors
Silicon materials for Tracking Sensors

Signal comparison for various Silicon sensors

Note: Measured partly under different conditions! Lines to guide the eye (no modeling)!

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -35-

silicon materials for tracking sensors1
Silicon materials for Tracking Sensors

Signal comparison for various Silicon sensors

Note: Measured partly under different conditions! Lines to guide the eye (no modeling)!

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -36-

silicon materials for tracking sensors2
Silicon materials for Tracking Sensors

Signal comparison for various Silicon sensors

Note: Measured partly under different conditions! Lines to guide the eye (no modeling)!

LHC

SLHC

n-in-p technology should be sufficient for Super-LHC at radii presently (LHC) occupied by strip sensors

highest fluence for strip detectors in LHC: The used p-in-n technology is sufficient

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -37-

silicon materials for tracking sensors3
Silicon materials for Tracking Sensors

Signal comparison for various Silicon sensors

Note: Measured partly under different conditions! Lines to guide the eye (no modeling)!

Beware:Signal shown and not S/N !

  • All sensors suffer from radiation damage
  • Presently three options for innermost pixel layers under investigation:
    • 3-D silicon sensors (decoupling drift distance from active depth)
    • Diamond sensors
    • Silicon planar sensors

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -38-

ongoing work open questions example i good performance of planar sensors at high fluence
Ongoing Work / Open Questions (Example I)- Good performance of planar sensors at high fluence -
  • Why do planar silicon sensors with n-strip readout give such high signals after high levels (>1015 cm-2 p/cm2) of irradiation?
    • Extrapolation of charge trapping parameters obtained at lower fluences would predict much lower signal!
    • Speculations on ‘charge multiplication’ effects as even CCE > 1 observed

1700V

800V

500V

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -39-

ongoing work open questions example ii performance of mcz silicon in mixed fields
Ongoing Work / Open Questions (Example II)- Performance of MCZ silicon in mixed fields -
  • Is MCZ silicon (n- and p-type) an option for SLHC detectors?
    • Protons induce predominantly defects that are positively charged
    • Neutrons induce predominantly defects that are negatively charged
    • Mixed Fields: Compensation?

[T.Affolder et al. RD50 Workshop, Nov.2008]

  • Mixed irradiations:
    • (a) Фeq= 5x1014 neutrons
    • (b) Фeq= 5x1014 protons
  • FZ (n-in-n)
  • MCZ (n-in-n)

500V

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -40-

ongoing work open questions example ii performance of mcz silicon in mixed fields1
Ongoing Work / Open Questions (Example II)- Performance of MCZ silicon in mixed fields -
  • Is MCZ silicon (n- and p-type) an option for SLHC detectors?
    • Protons induce predominantly defects that are positively charged
    • Neutrons induce predominantly defects that are negatively charged
    • Mixed Fields: Compensation?

[T.Affolder et al. RD50 Workshop, Nov.2008]

  • Mixed irradiations:
    • (a) Фeq= 5x1014 neutrons
    • (b) Фeq= 5x1014 protons
  • FZ (n-in-n)Mixed Irradiation: Damage additive!
  • MCZ (n-in-n)

500V

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -41-

ongoing work open questions example ii performance of mcz silicon in mixed fields2
Ongoing Work / Open Questions (Example II)- Performance of MCZ silicon in mixed fields -
  • Is MCZ silicon (n- and p-type) an option for SLHC detectors?
    • Protons induce predominantly defects that are positively charged
    • Neutrons induce predominantly defects that are negatively charged
    • Mixed Fields: Compensation?

[T.Affolder et al. RD50 Workshop, Nov.2008]

  • Mixed irradiations:
    • (a) Фeq= 5x1014 neutrons
    • (b) Фeq= 5x1014 protons
  • FZ (n-in-n)Mixed Irradiation: Damage additive!
  • MCZ (n-in-n)Mixed Irradiation: Proton damage “compensates” part of neutron damage (Neff)

500V

More charge collected at 500V after additional irradiation!!!

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -42-

summary detectors for slhc
Summary – Detectors for sLHC
  • At fluences up to 1015cm-2(outer layers of SLHC detector): The change of the depletion voltage and the large area to be covered by detectors are major problems.
    • MCZ silicon detectors could be a solution (some more work needed!)n-MCZ “no” space charge sign inversion under proton irradiation, good performance in mixed fields due to compensation of charged hadron damage and neutron damage (Neff compensation)
    • p-type silicon microstrip detectors show very encouraging results:CCE  6500 e; Feq=41015 cm-2, 300mm, immunity against reverse annealing!This is presently the “most considered option” for the ATLAS SCT upgrade
  • At fluences > 1015cm-2 (Inner SLHC layers or innermost upgraded LHC pixel)The active thickness of any silicon material is significantly reduced due to trapping.Collection of electrons at electrodes essential: Use n-in-p or n-in-n detectors!
    • Recent results show that planar silicon sensors might still give sufficient signal, (still some interest in epitaxial silicon and thin sensor options)
    • 3D detectors : looks promising, drawback: technology has to be optimized!Many collaborations and sensor producers working on this.
    • Diamondhas become an interesting option(not part of RD50 project)
  • SiC and GaN have been characterized and abandoned by RD50.

Further information about RD50 activities: http://cern.ch/rd50/Further R&D: RD42, RD39, ATLAS & CMS detector upgrade meetings, ATLAS IBL

Michael Moll – 11th ICAPTT conference, Como, 5-9.Oct.2009 -43-