1. DESY seminar 9.1.2007 1 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Overview History of silicon for tracking detectors & Basics History of silicon for tracking detectors & Basics From LHC tracker to SLHC tracker From LHC tracker to SLHC tracker Radiation effects in silicon - defect engineering Radiation effects in silicon - defect engineering Device engineering – radiation hard device design Device engineering – radiation hard device design Signal formation Signal formation Isolation techniques Isolation techniques Silicon detectors for SLHC Silicon detectors for SLHC n + -p strip detectors n + -p strip detectors n + -p pixel detectors n + -p pixel detectors 3D detectors 3D detectors Electronics considerations Electronics considerations Conclusions Conclusions

2. DESY seminar 9.1.2007 2 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC History and basics

3. DESY seminar 9.1.2007 3 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Position sensitive silicon detectors Planar diodes – structured detectors (Kemmer 1980) photolitografic processing

4. DESY seminar 9.1.2007 4 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC First considerations about radiation hardness for HEP - SSC (Detectors and Experiments for the Superconducting Super Collider, pg. 491, Snowmass 1984 1984 considerations for SSC Now 105 upra “Silicon strip detectors (near the beam pipe) appear to be limited to…≤ 10 32....the 10 32 limit could be optimistic.” ( PSSC Summary Report pg. 130, 1984) (Detectors and Experiments for the Superconducting Super Collider, pg. 491, Snowmass 1984 T. Kondo et al, Radiation Damage Test of Silicon Microstrip Detectors, pg. 612, Snowmass 1984

5. DESY seminar 9.1.2007 5 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC And we are we know now … LEP HERA, Tevatron LHC SLHC? e + e - 1.5∙10 31 cm -2 s -1 pp 10 35 cm -2 s -1 Silicon is a reliable detector technology Available on large scale (200 m 2 CMS) by many vendors with high yield 6’’ wafers are standard, 8’’ are coming Different silicon growing techniques can be exploited for sensor production (CZ, MCz, FZ, epi-Si) Many different electronics read-out ASICs were developed Also other devices are interesting for tracking: CCD, MAPS, DEPFETs … pp 1.4∙10 32 cm -2 s -1

6. DESY seminar 9.1.2007 6 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Silicon detectors today “Standard detector today” for HEP experiments (HERA (all), Belle, LEP, Tevatron) pitch 25 – few hundred microns readout strips in p + side (for SSD) or both sides (for DSD) - around 6 cm long AC/DC coupled 300  m thick produced on n type-standard float zone silicon n-type silicon of 2-15 k  cm resistivity poly-silicon or FOXFET biased on the readout side Multi guarding structure Physics reasons: superior position resolution (up to few microns), due to fine segmentation fast charge collection (t col ~ few ns) for 300  m thick sensors – high rate operation dE/dx possible operational at moderate voltages Signal ~ 22500e in 300  m C~1pF/cm

7. DESY seminar 9.1.2007 7 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC LHC & SLHC

8. DESY seminar 9.1.2007 8 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Main problems of a tracker at LHC: Loss of efficiency fast electronics (high series noise) charge trapping (loss of signal) high U bias, danger of break-down High power dissipation (8W/module for ATLAS-SCT) Need for running cool (leakage current) Need for storing cool to reduce V fd increase Large scale – complex services and links LHC – new challenge LHC properties  Proton-proton collider, 2 x 7 TeV Luminosity: 10 34  Bunch crossing: every 25 nsec, Rate: 40 MHz event rate: 10 9 /sec (23 interactions per bunch crossing)  Annual operational period: 10 7 sec  Expected total op. period: 10 years

9. DESY seminar 9.1.2007 9 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC ATLAS Overall length: 46m, diameter: 22m, total weight: 7000t, magnetic field: 2T CMS Overall length: 21.5m, diameter: 15m, total weight: 12500t, magnetic field: 4T

10. DESY seminar 9.1.2007 10 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Super LHC LHC upgrade  LHC (2007), L = 10 34 cm -2 s -1  (r=4cm) ~ 3·10 15 cm -2  Super-LHC (2015 ?), L = 10 35 cm -2 s -1  (r=4cm) ~ 1.6·10 16 cm -2 TID=4 MGy 5 years 2500 fb -1 CERN-RD48 CERN-RD50 ~5000e Inner Pixel Mid-Radius Short Strips Outer-Radius “SCT” Q>9000e Q>4000e Q>18000e Two main problems: Occupancy increase Radiation damage Phase 1: no major change in LHC L = 2.34 ∙10 34 cm -2 s -1 (higher beam current) Phase 2: major changes in LHC L = 4.6 ∙10 34 cm -2 s -1 with (BL/2,  c ) L = 9.2 ∙10 34 cm -2 s -1 with (fill all bunches) Phase 3: increase beam energy to 14 TeV (9 to 17 T magnets) 10 years 500 fb -1

11. DESY seminar 9.1.2007 11 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC ATLAS at SLHC (II) Initial studies show that other sub-detectors can be kept with small modifications and some with somewhat degraded performance also at SLHC! Long barrel proposal (other “Straw Man” design) ID ATLAS @ LHC ID ATLAS @ SLHC ID requires complete replacement, but keeping services at the same level! Time plan: R&D 2009, 2010 Construction phase, 2014 Commissioning

12. DESY seminar 9.1.2007 12 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC ATLAS at SLHC (III) Pixels 400x50  m 2 Short strips 3 cm x 50  m Long strips 12 cm x 80  m Simulation studies done to determine optimum segmentation to cope with high track multiplicities: 230 min. bias collisions/BC 10000 tracks for |  |<2.3 LHC x10 if BCT=25 ns x5 if BCT=12.5 ns SLHC

13. DESY seminar 9.1.2007 13 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Radiation damage in semiconductor detectors

14. DESY seminar 9.1.2007 14 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC The CERN RD50 Collaboration http://www.cern.ch/rd50 formed in November 2001 formed in November 2001 approved as RD50 by CERN June 2002 approved as RD50 by CERN June 2002 Main objective: Main objective: Presently 260 members from 53 institutes Development of ultra-radiation hard semiconductor detectors for the luminosity upgrade of the LHC to 10 35 cm -2 s -1 (“Super-LHC”). Challenges:- Radiation hardness up to 10 16 cm -2 required - Fast signal collection (Going from 25ns to 10 ns bunch crossing ?) - Low mass (reducing multiple scattering close to interaction point) - Cost effectiveness (big surfaces have to be covered with detectors!) RD50: Development of Radiation Hard Semiconductor Devices for High Luminosity Colliders Belarus (Minsk), Belgium (Louvain), Canada (Montreal), Czech Republic (Prague (3x)), Finland (Helsinki, Lappeenranta), Germany (Berlin, Dortmund, Erfurt, Freiburg, Hamburg, Karlsruhe, Munich), Israel (Tel Aviv), Italy (Bari, Bologna, Florence, Padova, Perugia, Pisa, Trento, Turin), Lithuania (Vilnius), Norway (Oslo (2x)), Poland (Warsaw(2x)), Romania (Bucharest (2x)), Russia (Moscow), St.Petersburg), Slovenia (Ljubljana), Spain (Barcelona, Valencia), Switzerland (CERN, PSI), Ukraine (Kiev), United Kingdom (Exeter, Glasgow, Lancaster, Liverpool, Oxford, Sheffield, Surrey), USA (Fermilab, Purdue University, Rochester University, SCIPP Santa Cruz, Syracuse University, BNL, University of New Mexico)

15. DESY seminar 9.1.2007 15 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Two types of radiation damage in detector materials:  Bulk (Crystal) damage due to Non Ionizing Energy Loss (NIEL)  Bulk (Crystal) damage due to Non Ionizing Energy Loss (NIEL) - displacement damage, built up of crystal defects – I. Increase of leakage current (increase of shot noise, thermal runaway) II. Change of effective doping concentration (higher depletion voltage, under- depletion) III. Increase of charge carrier trapping (loss of charge)  Surface damage due to Ionizing Energy Loss (IEL) - accumulation of charge in the oxide (SiO 2 ) and Si/SiO 2 interface – affects: interstrip capacitance (noise factor), breakdown behavior, …  Surface damage due to Ionizing Energy Loss (IEL) - accumulation of charge in the oxide (SiO 2 ) and Si/SiO 2 interface – affects: interstrip capacitance (noise factor), breakdown behavior, … ! Signal/noise ratio = most important quantity ! Radiation damage

16. DESY seminar 9.1.2007 16 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC particle Si s Vacancy + Interstitial Point Defects (V-V, V-O.. ) clusters E K > 25 eV E K > 5 keV Frenkel pair V I charged defects  N eff, V dep e.g. donors in upper and acceptors in lower half of band gap generation  leakage current Levels close to midgap most effective Influence of defects on the material and device properties Trapping (e and h)  CCE shallow defects do not contribute at room temperature due to fast detrapping

17. DESY seminar 9.1.2007 17 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Low leakage current Low full depletion voltage High speed Low noise High mobility & saturation field big bandgap High resistivity Low dielectric constant Cost-effective No type inversion Commercially available in large scale High crystalline quality & negligible rad-induced deep traps Main Selection Parameters Main Operative Characteristics Main Material Characteristics High CCE Negligible trapping effects High E field close r-o elect. Thin thickness but: higher capacitance but: higher e-h creation energy Low power Selecting rad-hard materials for tracker detectors at SLHC

18. DESY seminar 9.1.2007 18 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Wide band gap (3.3eV) Wide band gap (3.3eV)  lower leakage current than silicon Signal: Diamond 36e/  m SiC 51e/  m Si80e/  m Signal: Diamond 36e/  m SiC 51e/  m Si80e/  m  more charge than diamond Higher displacement threshold than silicon Higher displacement threshold than silicon  radiation harder than silicon (?) R&D on diamond detectors: RD42 – Collaboration http://cern.ch/rd42/ CCE at high fluences degrades even more in SiC and GaN than in Si. New Materials: Diamond, SiC, GaN

19. DESY seminar 9.1.2007 19 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Approaches to develop radiation harder tracking detectors Material engineeringMaterial engineering Device engineeringDevice engineering Change of detectorChange of detector operational conditions operational conditions Defect Engineering of Silicon Defect Engineering of Silicon Understanding radiation damage Understanding radiation damage Macroscopic effects and Microscopic defects Macroscopic effects and Microscopic defects Simulation of defect properties & kinetics Simulation of defect properties & kinetics Irradiation with different particles & energies Irradiation with different particles & energies Oxygen rich Silicon Oxygen rich Silicon DOFZ, Cz, MCZ, EPI DOFZ, Cz, MCZ, EPI Oxygen dimer & hydrogen enriched Si Oxygen dimer & hydrogen enriched Si Pre-irradiated Si Pre-irradiated Si Influence of processing technology Influence of processing technology Device Engineering (New Detector Designs) Device Engineering (New Detector Designs) p-type silicon detectors (n-in-p) p-type silicon detectors (n-in-p) thin detectors thin detectors 3D and Semi 3D detectors 3D and Semi 3D detectors Stripixels Stripixels Cost effective detectors Cost effective detectors Simulation of highly irradiated detectors Simulation of highly irradiated detectors Monolithic devices Monolithic devices CERN RD39 “Cryogenic Tracking Detectors”

20. DESY seminar 9.1.2007 20 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Change of Depletion Voltage V dep ( n-type material – RD48 results) “Type inversion”: N eff changes from positive to negative (Space Charge Sign Inversion) 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! 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! …. with time (annealing): before inversion after inversion neglecting double junction n+n+ p+p+ n+n+ p+p+ …. with particle fluence

21. DESY seminar 9.1.2007 21 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC MCz-n Helsinki  In FZ detectors irradiation introduces effectively negative space charge! The role of the oxygen in the Si (V fd (I))  For detectors irradiated with charged hadrons  RD50: High initial oxygen dimmer (O 2i ) MCz/Cz and Epitaxial silicon detectors  positive space charge (Bi-stable donors) Increase of V fd at high fluences is roughly the same in all O rich materials |Neff|~7·10 -3 cm -1  p !  For detectors irradiated with charged hadrons  RD48: Higher oxygen content  less negative space charge  Almost independent of oxygen content: Donor removal “Cluster damage”  negative charge After neutron irradiation all materials behave similarly and neutrons are 3x (except epi-Si) more damaging than charged hadrons!

22. DESY seminar 9.1.2007 22 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC beneficial and reverse annealing similar to that of n-type STFZ, DOFZ materials Do we undergo SCSI NO verified by TCT & annealing curves 300  m thick sensors Proton irradiated oxygen rich detectors (V fd (II)) End of LHC 500 V Positive space charge is compensated by negative formed during RA Reverse annealing time constants are prolonged by high concentration of O

23. DESY seminar 9.1.2007 23 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC S-LHC: L=10 35 cm -2 s -1 Most inner pixel layer  Parameters extracted at elevated annealing fit measurements at room temperatures very well  Very good reproducibility and working model (BA, constant damage, 1st order RA, 2nd order RA) operational period per year: 100 d, -7°C, Φ = 3.48·10 15 cm -2 beam off period per year 265 d, +20°C positive stable damage negative space charge during RA Compensation The scenario can be found where the N eff can be controlled. Increase of V fd is not a limiting factor for efficient use of Si detectors! G. Lindström et al. Thin n-type epitaxial Si detectors-CERN-scenario experiment (V fd (III))

24. DESY seminar 9.1.2007 24 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Neutrons: smaller increase of |Neff| with fluence than in any other material |g c |~5·10 -3 cm -1 no SCSI for  =50  cm ; SCSI for  >150  cm SCSI G. Kramberger et al., 8th RD50 workshop SMART coll., 8th RD50 workshop Neutron irradiated epitaxial Si detectors (V fd (IV)) 200  m,  max =2∙10 15 cm -2 V fd < 300 V 20<r<60 cm no SCSI neutrons n-type detectors Not easy to produce

25. DESY seminar 9.1.2007 25 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Trapping of the drifting charge (I) The  e,h was so far found independent on material;  resistivity  [O], [C]  type (p,n)  wafer production (FZ, Cz, epitaxial)  somewhat lower trapping at  eq >10 15 cm -2  (-10 o C, t=min Vfd) [10 -16 cm 2 /ns] 24 GeV protons 200 MeV/c pions (average ) reactor neutrons Electrons 5.6 ± 0.7 4.1 ± 0.5 Holes 6.6 ± 0.8 6.0 ± 0.4 electrons holes extrapolated values r~4cm r~20cm r~60cm for higher fluences Remember we have a mixture of pions and neutrons in experiments!

26. DESY seminar 9.1.2007 26 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Trapping of the drifting charge (II) Trapping probability decreases with temperature, but mobility also! Operation at lower T doesn’t improve CCE ! Neutron irr.  an @60 o C E ta [eV] Electrons 0.3±0.15 ~650 min 1.06±0.1 Holes -0.4±0.2 ~550 min 0.98±0.1 Confirmed also by ATLAS pixel test beam! T. Lari, Nucl. Inst. Meth. A518 (2004) 349.

27. DESY seminar 9.1.2007 27 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Leakage current  Damage parameter  (slope in figure) Leakage current per unit volume and particle fluence   is constant over several orders of fluence and independent of impurity concentration in Si  can be used for fluence measurement  Leakage current decreasing in time (depending on temperature)  Strong temperature dependence: Consequence: Cool detectors during operation! Example: I(-10°C) ~1/16 I(20°C) 80 min 60  C with time (annealing): …. with particle fluence:

28. DESY seminar 9.1.2007 28 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Device engineering

29. DESY seminar 9.1.2007 29 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Device engineering - Signal in Si detectors (I) 80  m pitch 18  m implant diode Q h =Q e =0.5 q 280  m hole electron p+p+ n+n+ Contribution of drifting carriers to the total induced charge depends on  U w ! U w simple in diodes and complicated in segmented devices! For track: Q e /(Q e +Q h )=19% in ATLAS strip detector sensing electrode all other electrodes Weighting field n+n+ segmentation

30. DESY seminar 9.1.2007 30 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Device engineering - Signal in Si detectors (II) drift current scalar field in which the carrier drifts Terms different for holes and electrons trapping term (  eff,e ~  eff,h ) drift velocity (  e ~3  h ) electrons get less trapped example of inverted p + -n 280  m fully depleted detector with 25  m pitch

31. DESY seminar 9.1.2007 31 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Device engineering - Signal in Si detectors (III) n+n+ better p+p+ worse  Segmented readout diode Segmented readout good  How to get maximum signal?  use of n + -n or n + -p device (electron collection) with pitch<<thickness  implant width close to pitch (depends on FE elec. – inter-electrode capacitance)  for a given cell size of a pixel detector even worse: p + readout (p + -n detector) even better: n + readout (n + -p, n + -n detector)

32. DESY seminar 9.1.2007 32 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Device engineering - Signal in Si detectors (IV) Carriers in this region would be trapped before reaching high E w ! It doesn’t matter if the region is depleted or not - under-depleted detectors would perform almost as good as fully depleted! Segmented readout p+p+ n+n+ p+p+ n+n+ electrons

33. DESY seminar 9.1.2007 33 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Device engineering Device engineering Trapping induced charge sharing p + strips (wider cluster) diode n + strips (higher signal) Signals in the neighbors few % of the hit strip Depends strongly on fluence position of the hit and electrode geometry! 81% 0 p+p+ n+n+ measuring p bulk ±U Incomplete charge collection due to trapping results in appearance of the charge in the neighboring strips! bipolar pulse observed in atlas test beam Y. Unno et al., IEEE Trans. NS 49(4) (2002) 1868

34. DESY seminar 9.1.2007 34 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Device engineering Isolation techniques n + -side readout (I) 3 techniques available (from n + -on-n technology): n+ oxide strip 1 strip 2 p+ p- substrate backplane + + + + electron layer isolation structure needed to interrupt the inversion layer between the strip S1S2S1S2S1S2 p-spray p-stop p-spray/p-stop Simulations needed for each design of a detector to find an optimum! high-field regions high-field region depends on Q ox C int, V BR improve with radiation (O ox ), worse initially C int, V BR degrade with radiation (O ox ), better initially compromise

35. DESY seminar 9.1.2007 35 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Silicon detectors for SLHC

36. DESY seminar 9.1.2007 36 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC n + -p short strip detectors (20<r<60 cm) Detector geometry: Thickness=300  m, strip pitch=80  m, implant width= 18  m, LHC speed readout (SCT128A-HC), beta source measurements p-in-n : oxygenated and standard FZ 25% charge loss after 5x10 14 p/cm 2 (23 GeV) 25% charge loss after 5x10 14 p/cm 2 (23 GeV) over-depletion is needed over-depletion is needed Much better performance (same charge 6x the fluence + under-depleted operation) V fd >2500 V V fd ~1200 V V fd P.P. Allport et al., IEEE Trans. NS 52(5) (2005) 1903. CCE~60 % n-in-p : standard FZ ~40% charge loss after 3x10 15 p/cm 2 (23 GeV) ~40% charge loss after 3x10 15 p/cm 2 (23 GeV) ~7000 e after 7.5x10 15 p/cm 2 (23 GeV) ~7000 e after 7.5x10 15 p/cm 2 (23 GeV) CCE~30 %

37. DESY seminar 9.1.2007 37 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Trapping times tend to longer than predicted at high fluences! T=-20 o C, V bias =900 V At first unexpected behavior of CCE(t) Possible explanation: Increase of V fd (not so important as electric field is still present close to electrodes) Annealing of electron trapping times n + -p short strip detectors (20<r<60 cm) CONFIRMED also by simulations! The reverse annealing is not critical as for LHC! recent neutron irradiated samples

38. DESY seminar 9.1.2007 38 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC TPG baseboard Bridging structure n+-p short strip detectors – super modules LBNL proposal (evolved from CDF run IIb) Liverpool proposal

39. DESY seminar 9.1.2007 39 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC n + -p short strip detectors – shot noise STFZ detectors Short strips at r=35 cm (3 cm x50  m) CR-RC shaping Short strips should have noise below 1000 e – dominated by series noise In order to keep the noise below the desired limit ENC leak <500e, T<-15 o C 25 ns shaping time P. Allport et al.

40. DESY seminar 9.1.2007 40 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Long strip detectors (r>60 cm) Present technology (STFZ p + -n) pushed to the higher radii may work – however practical issues cold/warm during the beam-off must be considered Present technology (STFZ p + -n) pushed to the higher radii may work – however practical issues cold/warm during the beam-off must be considered Better would be n + -p type detectors (regardless of the silicon type – neutron dominated damage) Better would be n + -p type detectors (regardless of the silicon type – neutron dominated damage) higher signal and possible use potentially of longer strips to reduce # of channels and have the same S/N higher signal and possible use potentially of longer strips to reduce # of channels and have the same S/N No ballistic deficit with BCT=12.5 ns No ballistic deficit with BCT=12.5 ns Smaller operational voltage needed and no critical issue if V fd >operational bias (safety) Smaller operational voltage needed and no critical issue if V fd >operational bias (safety)

41. DESY seminar 9.1.2007 41 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Planar n + -p pixel detectors ( r<20 cm) Pion dominated damage – choice of material for these detectors MCz or epi-Si! Detectors of some 200  m almost ideal choice if kept warm during beam-off period  Compensation of positive space charge with acceptors during RA (always fully depleted)  Annealing of electron trapping times – smaller effect of trapping  Smaller power dissipation due to smaller leakage current and bias voltage  Smaller shot noise Epi-Si,75  m n. irr diodes after annealing (reduction of V fd and electron trapping times) after segmentation (higher contribution of electrons) ~ 4000 e@10 16 cm -2

42. DESY seminar 9.1.2007 42 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC 10 years of LHC (4 cm) at 10 34 cm -2 s -1 10 years of SLHC (4 cm) 10 34 cm -2 s -1 (500V) (60,100,160V) (600 V) more charge at lower voltages (<300 V) with epi-Si Threshold needed on pixel FE electronics is for ATLAS and CMS pixels around 3500-4000 electrons! Can we hope for better electronics?

43. DESY seminar 9.1.2007 43 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Combine traditional VLSI processing and MEMS (Micro Electro Mechanical Systems) technology. Both electrode types are processed inside the detector bulk instead of being implanted on the wafer's surface. The edge is an electrode. Dead volume at the Edge < 5 microns! Essential for forward physics experiments and material budget 3D n + -p pixel detectors ( r<20 cm) S.I. Parker, C.J. Kenny, J. Segal, Nucl. Instr. and Meth. A395 (1997) 328.

44. DESY seminar 9.1.2007 44 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC 3D n + -p pixel detectors ( r<20 cm) Pros. Better charge collection efficiency Faster charge collection (depends on inter-column spacing) Reduced full depletion voltage and by that the power Larger freedom for choosing electrode configuration Cons. Columns are dead area (aspect ratio ~30:1) Spatially non-homogenous CCE (efficiency=function of position) Much higher electrode capacitance (hence noise), particularly if small spacing is desired – small drift length Availability on large scale Time-scale and cost

45. DESY seminar 9.1.2007 45 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Volume = 1.2 x 1.33 x 0.23 mm 3 3 electrode Atlas pixel geometry n-electrode readout n-type before irradiation - 12 k  cm Irradiated with neutrons

46. DESY seminar 9.1.2007 46 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Sketch of the detector: grid-like bulk contact ionizing particle cross-section between two electrodes n+n+ n+n+ electrons are swept away by the transversal field holes drift in the central region and diffuse towards p+ Contact (long tail) n-columns p-type substrate Functioning: Different geometry – 3D sct (RD50) C. Piemonte et al., IRST

47. DESY seminar 9.1.2007 47 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Different geometry – 3D sct 300 or 500  m 150  m Inter-column region depleted @ 12 V undepleted Thickness calculated from signal Diode like structure CCE measurements (slow shaping time) 3D-stc DC coupled detector (64 x 10 columns) 80  m pitch 80  m between holes 10  m hole diameter Focused IR laser of 7  m spot size 3 strips connected to amplifier

48. DESY seminar 9.1.2007 48 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Different geometry – 3D dct Passivation n+ doped 55um pitch 50  m 300  m p+ doped 10  m Oxide 0.4um 1um p+ doped Metal Poly 3  m Oxide Metal P-stop p+ 50  m TEOS 2um 5m5m p - type substrate Designed proposed by RD50 collaboration (IRST, CNM, Glasgow) much simplified process – no need for support wafer during production single sided processing with additional step of etching and B diffusion Performance equal to original design

49. DESY seminar 9.1.2007 49 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Electronics – deep sub micron CMOS (ATLAS pixel, CMS all)

50. DESY seminar 9.1.2007 50 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHC Electronics – BiCMOS Short shaping times (12.5 ns) large capacitances Bipolar transistors perform better in terms of noise-power (CMOS requires larger bias current) Bipolar SiGe transistors “married” to DSM-CMOS BiCMOS in atlas not radiation hard enough and not available anymore Around 4 times smaller power consumption than present design

51. DESY seminar 9.1.2007 51 G. Kramberger, Jožef Stefan Institute, Towards Radiation Hard Silicon Detectros at SLHCConclusions The ideal detector is the one which can be depleted all the time and kept at room temperature during beam-off periods – we are almost there! Sensor technology for SLHC tracker Sensor technology for SLHC tracker Long strips (present p + -n cost effective or n + -p) Long strips (present p + -n cost effective or n + -p) Short strips/pixel (n + -p on rad-hard material) Short strips/pixel (n + -p on rad-hard material) Pixel layers without innermost layer (n + -p pixels on rad-hard material) Pixel layers without innermost layer (n + -p pixels on rad-hard material)  Pixel layer at 4-6 cm (to be decided between diamond and silicon planar or 3D pixels) Electronics technology: all DSM-CMOS or BiCMOS (with SiGe bipolar part) for strips Electronics technology: all DSM-CMOS or BiCMOS (with SiGe bipolar part) for strips The most challenging will be engineering work (cooling, cabling, shielding, other services) The most challenging will be engineering work (cooling, cabling, shielding, other services) Prospects are good, but work ahead is enormous! Let’s wait to see first results from LHC, before …