Silicon Photomultiplier - characteristics and applications Nicoleta Dinu Laboratory of Linear Accelerator, IN2P3, CNRS, Orsay, France Seminar at Geneva University, DPNC, 21.05.2014 1 OUTLINE PART A: ◦ Silicon Photomultiplier (SiPM) Introduction on solid state photon detectors SiPM design and physics principle SiPM electrical and optical characteristics SiPM arrays PART B: ◦ SiPM applications Intra-operative probes for tumors localization during cancer surgery Compact imaging gamma camera (SIPMED) 2 PART A: Silicon Photomultiplier 3 Review of solid-state photon detectors (1) GM-APD APD P+ - Type N – Type Silicon ~ 4 µm PN or PIN + p+ n high electric field multiplication region -epilayer eh+ p+-type silicon (substrate) p-n junction, reversed Vbias – 0-3 V Gain = 1 p-n junction, reversed Vbias < VBD p-n junction, reversed Vbias > VBD Gain = M (~ 50-500) Gain → infinite - linear mode operation- -Geiger-mode operation-4 Review of solid-state photon detectors (2) p-n junction working in reverse bias mode Absolute reverse voltage Absolute reverse voltage • 0 < Vbias < VAPD (few volts) • G=1 • Operate at high light level (few hundreds of photons) GM-APD or SPAD APD Photodiode • • • • VAPD < Vbias < VBD G = M (50 - 500) Linear-mode operation Operate at medium light level (tens of photons) • • • • Vbias > VBD (Vbias-VBD ~ few volts) G Geiger-mode operation Can operate at single photon level 5 Geiger-Mode Avalanche Photodiode The first single photon detectors operated in Geiger-mode R.H. Haitz J. Appl. Phys., Vol. 36, No. 10 (1965) 3123 J.R. McIntire IEEE Trans. Elec. Dev. ED-13 (1966) 164 Rs=50 h GM-APD output GM-APD Rq n+ (K) p++ (A) -Vbias Passive quenching circuit Active resistor made of MOS transistor controlled by a fast electronics Active quenching circuit S. Cova & al., Appl. Opt., Vol. 35, No 12 (1996) 1956 6 SiPM cell – design & physics principle GM-APD (p-n junction) connected in series with quenching resistance RQ GM-APD and RQ – on the same substrate C. Piemonte, …, N. Dinu…, IEEE TNS, Vol. 54, Issue 1, 2007 Digital device Voltage (a.u.) Time (a.u.) Q = Q1 = Q2 = …= Qn Standard output signal No information on light intensity 7 SiPM – design & physics principle Parallel array of -cells on the same substrate ◦ Each -cell: GM-APD in series with RQ E Metal grid Rquench 10-100µ depth 1 mm OUT SiPM / FBK 1 mm 2-4µ 300µ epi layer SiPM / Hamamatsu E Si substrate SiO2 + Si3N4 VBIAS ’90s by V.M.Golovin & Z.Sadygov, Russian patents 1 mm depth pn junctions Geiger-Mode 1 mm 1 pixel fired 2 pixels fired 3 pixels fired Analog device Qtot = Q1 + Q2 + …= nQ1 Output signal number of fired cells that is the number of photons (if efficiency = 1) 8 SiPM – few examples of design & packages Hamamatsu HPK (http://jp.hamamatsu.com/) 10x10, 15x15 , 25x25, 50x50, 100x100µm2 cell size 1x1mm2 SensL (http://sensl.com/) 20x20, 35x35, 50x50, 100x100µm2 cell size 1x1 and 3x3 mm2 3x3mm2 FBK-IRST (http://advansid.com/home) 50x50µm2 pixel size KETEK (http://www.ketek.net/) 25x25, 50x50, 100x100µm2 cell size 1.2x1.2 mm2 3x3 mm2 6x6 mm2 9 SiPM characteristics: • DC measurements in the dark & room temperature • • • • Reverse and forward IV characteristics AC measurements in the dark & room temperature • Signal shape • Gain • Dark count rate Optical measurements at room temperature • Photon detection efficiency • Timing resolution Temperature dependence 10 DC characteristics @ 25°C N. Dinu et al., NIM A, 610, 2009 Overvoltage: V = VBIAS - VBD • Technical team: V. Chaumat, JF. Vagnucci • Lab course @ EDIT & MC-PAD schools at CERN, 2011 N. Dinu et al., NIM A, 610, 2009 Recovery time: cell RQCdiode 11 SIGNAL SHAPE @ 25°C Keithley Multimeter 2000 Vcc Pt100 Keithley 2611 Vbias & PicoA 0.01500MHz TDS 5054 500MHz, 5GS/s SiPM metallic box Climatic chamber ±0.1°C GPIB LabView Technical team: V. Chaumat, JF. Vagnucci, Z. Amara, C. Bazin rise RD(CD+CQ) fall slow RQ (CD+CQ) fall fast Rload (Ctot+Cg) N. Dinu et al., NIM A, 610, 2009 N. Dinu et al., NIM A, 610, 2009 12 GAIN @ 25°C Number of charge carriers developed during avalanche discharge Q C D CQ V C D CQ VBIAS VBD G qe qe qe G increases linearly with V = VBIAS – VBD the slope of linear fit of G vs. V Ccell = CD + CQ G and Ccell increase with cell geometrical dimensions N. Dinu et al., NIM A, 610, 2009 N. Dinu et al., NIM A, 610, 2009 C S i 0 A d 13 Dark count rate @ 25°C • The number of pulses/s registered by the SiPM in the absence of the light • It limits the SiPM performances (e.g. single photon detection) • Three main contributions: • Thermal/tunneling – thermal/ tunneling carrier generation in the depleted region looks the same as a photon pulse • After-pulses – carriers trapped during the avalanche discharging and then released triggering a new avalanche after the breakdown • Optical cross-talk – 105 carriers in an avalanche breakdown emit in average 3 photons with an energy higher than 1.14 eV (A. Lacaita et al. IEEE TED 1993) – these photons can trigger an avalanche in an adjacent µcell th=0.5pe th=0.5pe 14 Dark count rate @ 25°C N. Dinu et al., NIM A, 610, 2009 N. Dinu et al., NIM A, 610, 2009 DCR – linear dependence due to triggering probability V - non-linear at high V due to cross-talk and after-pulses V2 DCR scales with active surface Critical issues: Quality of epitaxial layer Gettering techniques 15 Photon Detection Efficiency (1) PDE N pulses N photons QE P01 geom QE P01 geom Technical team: V. Chaumat, JF. Vagnucci, C. Bazin 16 Photon Detection Efficiency @ 25°C (2) Hamamatsu cell SiPM’s from 2007 productions, 1x1 mm2 • p+n GM-APD on n-type substrate • Peak of PDE optimized for blue light (420 nm) N. Dinu et al., NIM A, 610, 2009 FBK & SensL cell • n+p GM-APD on p-type substrate • Peak of PDE optimized for green light (500-600nm) •PDE is depending on the SiPM cell structure • p+/n cell is more blue sensitive than n+/p • electron triggering probability is higher than hole triggering 17 Single photon timing resolution @ 25°C Two components : SPT • fast component of gaussian shape with σ O(100ps) R • due to photons absorbed in the depletion region • its width depends on the statistical fluctuations of the avalanche build-up time (e.g. photon impact position cell size) • slow component: minor non gaussian tail with time scale of O(ns) • due to minority carriers, photo-generated in the neutral beneath the depletion layer G. that reach the junction by FBK-irst SiPMregions single photon timing resolution Courtesy of G. Collazuol (not published) Collazuol et al., NIM A, 581, 2007 diffusion MePhI/Pulsar Poisson statistics: σ ∝ 1/√Npe 18 Thermal effects 19 Gain vs. bias voltage vs. temperature N. Dinu, A. Nagai, A. Para, not published T=-175°C T=+55°C T=-175°C SiPM Hamamatsu 1x1 mm2, 50x50m2 Production 2007 Breakdown voltage vs temperature T=+55°C SiPM Hamamatsu 3x3 mm2, 50x50m2 Production 2011 C.R.Crowell and S.M.Sze Appl. Phys. Letters 9, 6(1966) SiPM Hamamatsu 3x3 mm2, 50x50m2 Production 2011 SiPM Hamamatsu 1x1 mm2, 50x50m2 Production 2007 20 Gain vs. overvoltage vs temperature N. Dinu, A. Nagai, A. Para, not published SiPM Hamamatsu 3x3 mm2, 50x50m2 Production 2011 SiPM Hamamatsu 1x1 mm2, 50x50m2 Production 2007 8% 5% Slope → Cµcell=125±10fF Slope → Cµcell=90±5fF Capacitance & quenching resistance vs. temperature SiPM Hamamatsu 3x3 mm2, 50x50m2 Production 2011 SiPM Hamamatsu 1x1 mm2, 50x50m2 Production 2007 SiPM Hamamatsu 3x3 mm2, 50x50m2 Production 2011 38 m 42 m 50 m C S i 0 A d 50 m SiPM Hamamatsu 1x1 mm2, 50x50m2 Production 2007 21 Signal shape vs. temperature N. Dinu, A. Nagai, A. Para, not published T=+55°C T=+55°C T=-175°C T=-175°C fall slow 40ns@+55°C250ns@-175°C SiPM Hamamatsu 1x1 mm2, 50x50m2 Production 2007 fall slow 80ns@+55°C200ns@-175°C SiPM Hamamatsu 3x3 mm2, 50x50m2 Production 2011 Dark count rate vs. temperature T=+55°C T=+55°C T=-25°C T=-25°C SiPM Hamamatsu 1x1 mm2, 50x50m2 Production 2007 T=-100°C SiPM Hamamatsu 3x3 mm2, 50x50m2 Production 2011 T=-100°C 22 Arrays of SiPM - monolithic Nicoleta Dinu 23 Arrays of SiPM - discrete Nicoleta Dinu 24 PART B: SiPM applications – medical imaging 25 Techniques of nuclear imaging • Principle Marking Detection Techniques of nuclear imaging Pharmaceutical product: • organic molecules + radioactive isotope • camera, topographies • Radioactive isotopes • 99mTc, 123I, 201Tl, 18F, 11C • Emitters , + or - • Techniques Cancer diagnostic (homographs) TEMP Cancer therapy Per-operative detection systems TEP 26 SIPMED project High resolution hand-held radiation detector for therapeutic purposes SIPMED imaging camera Radio-guided surgery collimator LaBr3(Ce) scintillator 5.5 cm 16 (4x4) SiPM arrays field of view: 30 cm2 6 cm 256 readout channels (ASIC) on miniaturized electronics boards Collaboration IMNC, LAL, Hôpital Lariboisière Detection system requirements in surgical conditions • reduced size and weight • versatility of readout electronics • adapted for sterile environment S11828-3344M Hamamatsu HPK • 4x4 monolithic SiPM array • mounted on a SMD package • Each SiPM = one readout channel: •3x3 mm2, 3600 cells, each cell - 50x50 m2 IV of monolithic SiPM arrays from HPK Keithley 2611 Hi Lo 23 arrays (368 IV’s) 1.5V VBD range 256 IV’s 16 over 23 arrays selected for SIPMED 0.8V VBD range 28 Characteristics uniformity Plots by: A. Nagai VBD SIPMED camera Board SiPM 3 Board SiPM 4 Board SiPM 3 Board SiPM 4 Board SiPM 2 Board SiPM1 Board SiPM 2 Board SiPM 1 Idark @ VBIAS =72.5V Idark @ overvoltage =1V Board SiPM 3 Board SiPM 3 Board SiPM 4 Board SiPM 4 Board SiPM 1 Board SiPM 2 Ipost-BD qGDCR Board SiPM 1 Board SiPM 2 29 Elementary module of SIPMED camera USB interface T. Ait Imando et al., PoS 2012 Front side Elementary module Field of view: 8 cm2 28.6 mm Back side Board 1: 4 (2x2) SiPM arrays 64 readout channels Board 2: 2 EASIROC chips 64 readout channels 2 ADC 12 bits Board 3: FPGA FTDI & USB 30 SIPMED camera 256 SiPM’s = 256 readout channels • Optical and electrical tests under progress SIPMED camera Weight: 1.2 kg Pictures by courtesy of L. Menard TRECaM camera based on MAPMT Weight: 2.2 kg 31 Preliminary characteristics of SIPMED camera SIPMED energy resolution:10.5% @ 122 keV Good linearity TRECaM energy resolution:12.9% @ 122 keV SIPMED spatial resolution:1.23 mm@ 122 keV TRECaM spatial resolution:1.36 mm @ 122 keV Plots by courtesy of L. Menard 32 Conclusions and perspectives Detector point of view: understanding of device fundamentals Detailed physical models of avalanche multiplication, triggering probability Reducing DCR and afterpulsing contributions Improvement in fast timing applications Temperature dependence of different parameters for stable operation PDE improvements in UV & IR regions . Applications point of view Build large detection area Uniform electrical and optical characteristics Low dead area (3D interconnection - cost) Development of dedicated ASIC’s involving multichannel readout electronics Studies of radiation hardness for application in high energy physics experiments 33 Additional slides 34 Read-out electronics of SIPMED Board SIPMED2 Front side Back side •2 EASIROC chips/ elementary module • two-channels externals ADC 12-bit, 2MSPS • EASIROC chip • 32 channels • 8-bit input DAC, 0-2.5V range • Low and high voltage pre-amplifiers, adjustable gain • charge measured at maximum amplitude of slow shapers (50 to 175 ns peaking time) by two Track and Hold blocks • fast trigger line, made of a fast shaper and a discriminator, provides the hold signal Board SIPMED3 Front side Back side • ALTERA ciclone III FPGA • FTDI FT2232H (USB protocol 2.0 Hi-speed, 440MBit/s) •USB mini-connector for power supply and PC communication •DC/DC converter for SiPM bias 35 Radiation damage • Radiation damage effects on SiPM: • increase of dark count rate due to introduction of generation centers • increase of after-pulse rate due to introduction of trapping centers • may change VBD, leakage current, noise, PDE…. 36
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