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DEPFET Status

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DEPFET Status. DEPFET Principle Readout modes Projects: XEUS WIMS ILC ILC Testbeam results Summary & Outlook. Univ. of Bonn: M.Karagounis, R.Kohrs, H.Krüger, M. Mathes, L.Reuen, C.Sandow, E.von Törne, M.Trimpl, J.Velthuis, N.Wermes Univ. of Mannheim: P.Fischer, F.Giesen, I.Peric - PowerPoint PPT Presentation

Text of DEPFET Status

  • DEPFET StatusDEPFET PrincipleReadout modesProjects:XEUSWIMSILCILC Testbeam resultsSummary & OutlookUniv. of Bonn: M.Karagounis, R.Kohrs, H.Krger, M. Mathes, L.Reuen, C.Sandow, E.von Trne, M.Trimpl, J.Velthuis, N.Wermes

    Univ. of Mannheim: P.Fischer, F.Giesen, I.Peric

    Politecnico di Milano:M. Porro

    MPI Halbleiterlabor Munich:O Hlker, S. Herrmann, L.Andricek, G.Lutz, H.G. Moser, R.H.Richter, M.Schnecke, L.Strder, J.Treis, P.Lechner, S. Wlfel

    THCA of Tsinghua Univ.:C. Zhang, S.N. Zhang

  • DEPFET PrincipleA p-FET transistor is integrated in every pixel.By sidewards depletion potential minimum created below internal gate.Electrons, collected at internal gate, modulate transistor current

  • DEPFET PrincipleAdvantages:Fast signal collection due to fully depleted bulkLow noise due to small capacitance and amplification in pixelTransistor can be switched off by external gate charge collection is then still active !Non-destructive readout

    Disadvantages:Need to clear internal gate. This still requires high voltages.

    2 readout modes:Source follower mode readout. Signal is voltage (XEUS)Drain readout. Signal is current (WIMS&ILC)required

  • SOURCE FOLLOWERConstant bias current IBias providedCharge at internal gate translates into source voltage node changeSpeed depends on overall load capacitanceSlow (tCL/gm3s), but excellent noise

  • DRAIN readoutMeasure Idrain directlyFast response: limited by RC time of input resistance CURO and Cload (~ns)

  • DEPFET ApplicationsDEPFET under study for:XEUSExploring the early universe by imaging spectroscopy in the X-ray bandNeed noise < 4e-Source follower modeWIMSWide-band Imaging and Multi-band Spectrometer, part of Chinas spacelab missionDrain readoutILCNeed row rates of 20MHzDrain readout

  • XEUSExploring the early universe by imaging spectroscopy in the X-ray band

    Detector:Device active area 7.68 x 7.68 cm2Monolithic sensor integrated onto a single 6 waferDevice thickness 450 mPixel size 75 x 75 m2Position resolution ca. 30 mTotal 1024 x 1024 pixel cellsTotal readout time / frame 1.25 msProcessing time per detector row 2.5 s

  • Excellent noiseSingle pixel device 10 s shapingRoom temperature (22 C)

  • Excellent noiseLarge structure (64x64):75 x 75 m2 pixel size 45 m gate circumference / 5 m gate lengthDrain in center of pixelCut gate geometryCurved edgeDouble metal

    Operated at:Pixel current 30 ALine processing time 25 s

  • WIMSWide-band Imaging and Multi-band Spectrometer (WIMS) is part of Chinas spacelab mission .Observe high-energy bursts, transients and fast-varying sources over a broad spectral range simultaneously

    Using Macro pixelsPixel size 0.5x0.5 mm2Si-drift chamber readout using DEPFET

  • DEPFET for ILCBasic system ClearingILC requirementsLadder proposalPower consumptionThinningRadiation hardnessTestbeam results

  • Basic systemSelect and Clear signals provided by SWITCHER 64 x 2 outputsMax V = 25V

    Read out row-wise: CUROcurrent based read out128 channelsCDS real time hit finding & zero-suppressionrow rate up to 24 MHz

  • HighE vs non-HighEHighE extra n-type implantMoves internal gate deeper into bulkClearing takes places deeper in the bulkLower signals, but easier clearingclearInternal gatechannelOptional HighE implant

  • ClearingCURO measures: Isig,i+Iped,i & Iped,i+1Need to remove all charge such that Iped,i+1=Iped,iCOMPLETE CLEAR possible for HighE with low voltages (~7V) possible to make radhard SWITCHER in standard CMOSHighE

  • ILC requirementsTime structure: 1 train of 2820 crossings in ~1 ms every ~200msHit density: for r = 15 mm: ~ 100 tracks / mm2 / trainRow readout rate: > 20 MHz Occupany < 0.5 %Radiation length: ~0.1% X0 per layerthinned sensors (50 m) low power consumptionRadiation tolerance: 200 krad (for 5 years operation) Resolution: few m ( pixel size 25 x 25 m2)

  • Ladder proposalModules have active area ~13 x 100 mm2Read out on both sides.Detectors 50m thick, with 300m thick frame yields 0.11% X0SWITCHER & CURO chips connected by bump bondingSWITCHERCURO

  • ILC PowerMeasured Power Dissipation:Switcher: 6.3 mW per active channel at 50MHzCURO: 2.8 mW / channelAssumed Power Dissipation of DEPFET Sensor:0.5 mW per active pixelduty cycle: 1/200Only active pixel dissipate power1024 active pixels per module8 modules in Layer 1 => 8192 active pixelsExpected Power Dissipation in Layer 1Sensor: 8192 x 0.5 mW / 200 = 20 mWSwitcher: 16 x 6.3 mW / 200 = 0.5 mWCuro: 8192 x 2.8 mW / 200 = 114 mW For Layer 1 Sum: 135 mWFor 5 Layer DEPFET Vertex Detector: Total ~ 3.6 W no active cooling

  • ThinningThinning technology for active area established

  • Radiation hardnessIrradiations with 60Co and X-rays (~17keV) up to ~1Mrad (SiO2) Threshold shift of the MOSFET (~4V) can be compensated by bias voltage shift

  • TestbeamDESY test beam with 6 GeV e- Bonn ATLAS telescope system:double sided strip detectorspitch 50 m (no intermediate strips)readout rate 4.5 kHz (telescope only)

    DEPFET: 128x64 (28.5x36 m2)450 m thickFrame time 1.8 ms

  • Pedestal & NoisePedestal: average signal after hit removalNoise: standard deviation after pedestal, common mode and hit removal

  • ClusteringLook for clusters:Seedpixel largest signal seed cut >5NeighboursNeighbour cut >2Combine signals seed & neighborsS/N3x3=125.90.2Noise higher than expectedNext generation expect to reduce noise by factor 2

  • Position resolutionHit positions reconstructed using the CoG algorithmNote: pixelsize X=36m Y=28.5mTerrible, but due to multiple scattering

  • Multiple scatteringEelectron only 6GeVTelescope planes 10cm apartMinimize effect scattering by selecting hard tracks using 2 cutPrice: lose statistics

  • Multiple scattering (II)Performed simulation.Using Fraction remaining tracks, telescope uncertainty can be estimated.From CERN testbeam know that intrinsic~5-6m, but not compared S/Ntel X=9.710.02m, Y=9.310.02m

  • HighE matrixHighE implant moves internal gate into bulkLower signalEasier clearing

    Results:S/N3x3=99.50.1X=9.110.03m, Y=8.800.03mSomewhat larger clusters yield better position resolution

    intrinsicXY5m4.84.36m1.9--

  • SummaryDEPFET integrates MOSFET in fully depleted bulk. Developed towards: XEUS mission:Slow readout(source follower mode)Excellent noise (~2.2e-)WIMS missionVery large pixels (0.5x0.5mm2) Si-drift chamber readout by DEPFETFast(er) readout (noise=19e-)

  • Summary (II)Developed towards ILC. Meets already demands onRadiation length (0.11 X0)Radiation hardness (Vth [email protected])Power consumption (
  • OutlookImproving the system to increase readout speed.Individual parts already function well at ILC speedTestbeam at DESY (6GeV electrons) with better mechanics and at CERN. Goals:Improve S/NTest zero suppressionBuild 512x512 matrix

  • Author listUniv. of Bonn: M.Karagounis, R.Kohrs, H.Krger, M. Mathes, L.Reuen, C.Sandow, E.von Trne, M.Trimpl, J.Velthuis, N.Wermes

    Univ. of Mannheim: P.Fischer, F.Giesen, I.Peric

    Politecnico di Milano:M. Porro

    MPI Halbleiterlabor Munich:O Hlker, S. Herrmann, L.Andricek, G.Lutz, H.G. Moser, R.H.Richter, M.Schnecke, L.Strder, J.Treis, P.Lechner, S. Wlfel

    THCA of Tsinghua Univ.:C. Zhang, S.N. Zhang