Advances in multi-pixel Geiger mode APDs (Silicon Photomultipliers).

Transcription

1 Advances in multi-pixel Geiger mode APDs (Silicon Photomultipliers). Yuri Musienko Northeastern University, Boston & INR, Moscow INSTR-8, Novosibirsk, Y. Musienko 1

2 Outline SiPM: principle of operation SiPM parameters, important for HEP applications New developments Radiation hardness Summary INSTR-8, Novosibirsk, Y. Musienko 2

3 APD s operated in Geiger mode High gain operate APDs over breakdown Geiger mode APDs Single pixel Geiger mode APD s developed long time ago ( see for example: R.Haitz et al, J.Appl.Phys. ( )) Planar APD structure Passive quenching circuit Single pixel devices are not capable of operating in multi-photon mode Sensitive area is limited by dark count and dead time (few mm 2 Geiger mode APD can operate only at low temperature, needs active quenching ) Solution: Multipixel Geiger mode APD (MPGM APD) INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 3

4 First design (MRS APD, 1989) The very first metall-resitor-smiconductor APD (MRS APD) proposed by A. Gasanov, V. Golovin, Z. Sadygov, N. Yusipov (Russian patent #172881, from 1/11/1989 ). APDs up to 5x5 mm 2 were produced by MELZ factory (Moscow). Few % photon detection efficiency for red light was measured with.5x.5 mm 2 APD. Good pixel-topixel uniformity. Small geometrical efficiency. Very low QE for green and blue light. LED pulse spectrum (A. Akindinov et al., NIM387 (1997) 231) INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 4

5 Developers and producers Since 1989 many GM APD structures were developed by different developers: CPTA/Photnique (Moscow/Geneva) Zecotek (Singapur) MEPhI/Pulsar (Moscow) Hamamatsu Photonics (Hamamatsu, Japan) SensL (Cork, Ireland) RMD (Boston) MPI Semiconductor Laboratory (Munich, Germany) FBK-irst (Trento, Italy) Every producer invented their own name for this device: MRS APD, MAPD, SiPM, SSPM, SPM, G-APD INSTR-8, Novosibirsk, Y. Musienko 5

6 Structure and principles of operation Picture from talk of E. Grigoriev at Como 21 Geiger avalanche is quenched by an individual pixel resistor (from 1kΩ to several MΩ). It contains 1 2 pixels/mm 2, made on common substrate and connected together Each pixel works as a binary device MGAPD is pixellated silicon avalanche photodiode operated in Geiger mode (~1-2% over breakdown voltage) For small light pulses (N g <<N pixels ) device as a whole works as an analog detector INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 6

7 Counts SiPMs pixel-to-pixel uniformity Green-red light sensitive APD, low amplitude light signals, U=43V, T=-28 C ADC ch# MPGM APDs/SiPMs have very good pixel-to-pixel signal uniformity. Pedestal is well separated from the signal produced by single fired pixel Q 1. INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 7

8 Parameter definition: Gain Each pixel works as a digital device 1,2,3... photons produce the same signal Q 1 =C pixel *(V-V b ) (or Single Pixel Charge). Multi-pixel structure works as a linear device, as soon as N pe =N g *QE<<N, N is a total number of pixels/device Measured charge : Q output =N pe *Gain, It was found by many groups that : Gain Q 1, More than 1 pixel is fired by one primary photoelectron! Gain=Q 1 *n p, where n p is average number of pixels fired by one primary photoelectron. There are 2 reasons for this discrepancy: - optical cross-talk between pixels - after-pulsing (one pixel can be fired more than 1 time during light flesh) INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 8

9 Gain and Single Pixel Charge Q C ( V V 1 pix B ) M Q 1 fired N pixels INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 9

10 PDE(515nm) [%] Counts Photon detection efficiency MEPhI/PULSAR APD Bias [V] T= 22 C T=-28 C Photon detection efficiency (PDE) is the probability to detect single photon when threshold is < Q1. It depends on the pixel active area quantum efficiency (QE), geometric factor and probability of primary photoelectron to trigger the pixel breakdown P b (depends on the V-V b!!, V b is a breakdown voltage). PDE (l, U,T) = QE(l)*G f *P b (U,T) MEPhI/PULSAR APD, U=57.5 V, T=-28C INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) ADC, ch. To determine <N pe > in light pulse one can use well known property of the Poisson distribution : <N pe > = - ln(p()) Average number of photons <N g > in LED pulse can be measured using calibrated photo-sensor. Then: PDE(l) = <N pe >/ <N g >

11 Breakdown initiation probability Because of the higher ionization coefficient, the electron triggering probability is always higher than that of holes Ionization coefficients for electrons and holes in silicon INSTR-8, Novosibirsk, Y. Musienko 11

12 Geometric factor INSTR-8, Novosibirsk, Y. Musienko 12

13 PDE [%] PDE [%] Structure for green/red light Absorption length for light in silicon B. Dolgoshein et. al., An advanced study of silicon photomultiplier, ICFA-21 MEPhI/PULSAR APD, T=22C, U=59 V CPTA/Photonique APD T=22 C Wavelength [nm] (Y. Musienko, Beaune-5) Wavelength [nm] (Y. Musienko, PD-7, Kobe) INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 13

14 PDE (%) Doping conc. (1^) [1/cm^3] E field (V/cm) Improved blue sensitivity To improve sensitivity for blue/uv light structure with shallow junction (~1 nm) was produced Shallow-Junction SiPM 2 n + p 7E Doping Field 6E+5 5E E E E+5 1.6E E+5 1.4E+1 1.2E+1 1.E+1 8.E+ 6.E+ 4.E+ 2.E+ 4V 3.5V 3V 2.5V DV=2V 36V 36.5V 37V 37.5V 38V depth (um) (G. Pauletta: PD7, Kobe, Japan) E+.E Wavelength (nm) INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 14

15 PDE [%] Blue sensitive G-APD Another solution: reversed APD structure. In reversed structure electrons initiate the avalanche breakdown Measured using t technique described in NIMA 567 (26) p T=22 C HPK S C p - -epi n ++ -subst Wavelength [nm] (Y. Musienko, PD-7, Kobe) K.Yamamoto, PD-7, Kobe (optical crosstalk and after-pulses were not taken into account) INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 15

16 Optical cross-talk Hot-carrier luminescence: 1 5 carriers produces ~3 photons with an wavelength less than 1 mm Increases with the gain! Optical cross-talk causes adjacent pixels to be fired increases gain fluctuations increases noise and excess noise factor! Solution: optically separate pixels with grooves INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 16

17 Counts Counts Single electron spectrum When V-V b >>1 V typical single pixel signal resolution is better than 1% (FWHM)). However an optical cross-talk results in more than one pixel fired by single photoelectron. This results in deterioration of SiPM SES and SES MEPhI/PULSAR APD, U=57.5V, T=-28 C 1 1 SES CPTA APD, U=42 V, T=-28 C ADC ch ADC ch. INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 17

18 Number of fired pixels Excess Noise Factor and in an increase of the SiPM excess noise factor MEPhI/PULSAR APD T= 22 C T=-28 C F 1 M 2 M Single Pixel Charge*1 6 INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 18

19 dark rate, Hz The dark rate of the SiPM for different gains in dependence on the level of the threshold gain 7*1 5 gain 1*1 6 gain 1.3*1 6 Optical cross-talk increases the dark count at high electronics thresholds (E.Popova, CALICE meeting) Threshold, pixels INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 19

20 Number of fired pixels Single Pixel Charge*1 6 Gain*1 6 Gain is voltage and temperature dependent SiPM gain and PDE are temperature dependent MEPhI/PULSAR APD T= 22 C T=-28 C Bias [V] MEPhI/PULSAR APD T= 22 C T=-28 C Bias [V] MEPhI/PULSAR APD T= 22 C T=-28 C Single Pixel Charge*1 6 INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 2

21 Signal amplitude [ADC ch.] Amplitude [ADC ch.] Response temperature sensitivity CPTA APD 4 35 T=-25 C 3 T= 22 C Bias [V] Hamamatsu MPPC T=-25 C T= 22 C Bias [V] LED signal was measured in dependence on bias at 2 temperatures. During low temperature measurements (T=-25 C) G-APDs were placed inside commercial freezer (LED was kept at room temperature) CPTA/Photnique: dvb/dt=-2 mv/c Hamamatsu: dvb/dt=-5 mv/c INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 21

22 -1/A*dA/dT [%] -1/A*dA/dT [%] Temperature coefficient CPTA APD Bias [V] S C HPK MPPC Bias [V] k T =da/dt*1/a, [%/ C] INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 22

23 Optical cross-talk reduction To reduce optical cross-talk CPTA was the first to introduce trenches separating the neighbouring pixels (E. Grigoriev Como 21) INSTR-8, Novosibirsk, Y. Musienko 23

24 Excess Noise Factor F SiPMs with reduced optical cross-talk SiPM without trenches SiPM with trenches MEPhI/PULSAR APD T= 22 C T=-28 C CPTA APD Bias [V] Bias [V] INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 24

25 Dark Count [khz] The dark rate of the SiPM trenches in dependence on the discriminator threshold V 33 V Threshold [fired pixels] CPTA/Photonique SSPM with trenches INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 25

26 SiPM timing SiPMs have excellent timing properties Measured with MEPhI/Pulsar SiPM using single photons (B. Dolgoshein, Beaune-2) Measured with 1 mm SPAD using single photons INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 26

27 Linearity Linearity of SiPM is determined by its total number of pixels In the case of uniform illumination: This equation is correct for light pulses which are shorter than pixel recovery time, and for an ideal SiPM (no crosstalk and no after-pulsing) (B. Dolgoshein, TRD5, Bari) INSTR-8, Novosibirsk, Y. Musienko 27

28 Micro-pixel APDs with large dynamic range Z. Sadygov, Beaune-5 Micro-well structure with multiplication regions located in front of wells at 2-3 mm depth was developed by Z. Sadygov. MAPDs with 1 15 pixels/mm 2 were produced. Such devices are good for calorimetry applications. M.Golubeva et.al. LONGITUDINALLY SEGMENTED LEAD/SCINTILLATOR HADRON CALORIMETER WITH MICROPIXEL APD READOUT (this conference) INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 28

29 Voltage (V) Afterpulse/pulse After-pulsing C. Piemonte: June 13 th, 27, Perugia Tint = 6ns Tint = 1ns y =.67x x y =.68x x E-8 1.E-8 3.E-8 5.E-8 7.E-8 Time (s) Voltage (V) Events with after-pulse measured on a single micropixel. After-pulse probability vs bias Solution: cleaner technology or longer pixel recovery time INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 29

30 Large area SiPMs SiPMs with up to 3x3 mm 2 area produced by many companies: Hamamatsu, CPTA/Photonique, Pulsar, Zecotek, SensL, FBK-irst 1x1mm 2x2mm 3x3mm (36 cells) 4x4mm (64 cells) FBK-irst SiPMs, C. Piemonte: June 13 th, 27, Perugia INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 3

31 Radiation hardness studies Motivation: SiPMs will be used in HEP experiments Radiation may cause: Fatal SiPM damage (SiPM can t be used after certain absorbed dose) Dark current and dark count increase (silicon ) Change of the gain and PDE vs. voltage dependence (SiPM blocking effects due to high induced dark carriers generation-recombination rate) Breakdown voltage change INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 31

32 Radiation damage of MPPCs using gammas from Co 6 Matsubara, PD-7, Kobe Infrared emission (similar effects were seen with irradiated linear APDs INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 32

33 Radiation damage of SiPMs using protons Protons like 1 MeV neutrons produce defects inside silicon. Increase of the dark current: I d ~a*f*v*m*k, a dark current damage constant [A/cm]; F particle flux [1/cm 2 ]; V silicon active volume [cm 3 ] M SiPM gain k NIEL coefficient 2 MeV protons, M.Danilov arxiv: v1 INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 33

34 PDE(515nm) [%] PDE(515nm) [%] Dark Current [mka] PDE(515nm) [%] Irradiation studies at PSI (82 MeV protons) 23 SiPMs from 4 different producers irradiated at PSI last week 1*1 1 4 MeV/c (82 MeV kinetic energy) protons/cm 2 in 4 steps NIEL factor is ~2 times of 1 MeV neutrons, Total flux: 1*1 1 protons/cm 2, equivalent to ~2*1 1 1 MeV neutrons/cm 2 Gain, PDE, Id, Dark count vs. voltage were measured before irradiation Irradiation # "HPK_1mm_#535" (U=69.5V) "HPK_1mm_#535"(U=7.1V) "HPK_1mm_#535"(U=7.7V) before irr. after irr. CPTA# Bias [V] Hamamatsu #534 before irr. after irr before irr. after irr. FBK_K Bias [V] Bias [V] Actve area of SiPMs ~1 mm 2 INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 34

35 Dark Count [khz] Effective Thickness [mm] Dark Count [khz] Dark Count [khz] Dark Count/PDE(515nm) Dark Count vs. bias 2 month after irradiation Hamamatsu #534 before irr. after irr before irr. after irr. Bias [V] FBK_K Bias [V] CPTA#3 FBK_K1 Hamamatsu #534 Dark count increase PDE(515nm) Effective thickness (a Si = 4*1-17 A/cm) CPTA#3 FBK_K1 Hamamatsu # before irr. after irr. CPTA# Bias [V] PDE(515nm) INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 35

36 Summary Significant progress in development of SiPMs during recent 2-3 years: High PDE~3-4% for blue-green light (CPTA/Photonique, Hamamatsu) Reduction of dark count at room temperature (~1-3 khz, Hamamastu) Low cross-talk (<5-1%, CPTA/Photonique, FBK) Low temperature coefficient (~.3%/C, CPTA/Photonique) Fast timing (~5 ps (RMS) for single photons) Large dynamic range (1 15 pixels/mm 2, Dubna/Zecotek) Large area (3x3 mm 2, CPTA/Photonique, Hamamatsu, FBK, SensL, Dubna/Zecotek ) All this (together with understanding of radiation hardness issues) makes these devices excellent candidates for application in HEP experiments (see presentations of T.Ijima, P.Krizhan, A.Reshetin, D.Renker, V.Rusinov, S.Schuwalow, Yu.Kudenko, A.Ivashkin ) INSTR-8, Novosibirsk, Y. Musienko (Iouri.Musienko@cern.ch) 36