High-Density-cell (HD) NUV Silicon Photomultipliers produced at FBK - - PowerPoint PPT Presentation

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High-Density-cell (HD) NUV Silicon Photomultipliers produced at FBK - - PowerPoint PPT Presentation

Dec 15, 2022 125 likes •324 views

High-Density-cell (HD) NUV Silicon Photomultipliers produced at FBK F. Acerbi, A. Ferri, G. Zappal, A. Gola, G. Paternoster, N. Zorzi, C. Piemonte Silicon ph Silicon phot otom omult ultipliers ipliers Flash of 3 photons current 3X

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SLIDE 1

High-Density-cell (HD) NUV Silicon Photomultipliers produced at FBK

  • F. Acerbi, A. Ferri, G. Zappalà,
  • A. Gola, G. Paternoster, N. Zorzi, C. Piemonte
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SLIDE 2
  • Jul. 2015

Fabio ACERBI - PhotoDet 2015

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Performance parameters:

1. Photon-detection efficiency (PDE) 2. Primary noise (primary DCR) 3. Correlated noise: 1. Afterpulsing 2. Optical Crosstalk 4. Photon number resolution 5. … Timing & Energy resolution

Silicon Silicon ph phot

  • tom
  • mult

ultipliers ipliers

Flash of 3 photons

few tens of mm size

time current

photon arrival

3X elementary pulse

http://www.ketek.net/

http://advansid.com/

  • Fill Factor
  • GAIN
  • Semiconductor properties
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SLIDE 3
  • Jul. 2015

Fabio ACERBI - PhotoDet 2015

3

SiPM SiPM te tech chno nolog logy y at at FB FBK

RGB SiPM NUV SiPM

SPAD size: 40mm Fill factor: 60% Peak PDE: 33% Max PDE @ 550nm ENF: ~1.7 DCR ~ 300 kHz SPAD size: 40mm Fill factor: 60% Peak PDE: 40% Max PDE @ 400nm ENF: ~1.5 DCR: < 100kHz

RGB-HD SiPM

p-on-n junction

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SLIDE 4
  • Jul. 2015

Fabio ACERBI - PhotoDet 2015

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  • Improved substrate

Minority carrier lifetime reduced ~ 2 order of magnitude  lower delayed correlated noise

New New NUV NUV SiP SiPM M – tech techno nologica logical l improveme improvements nts

AP DiCT DeCT & AP

primary pulse

Old substrate new substrate

  • F. Acerbi et. al., IEEE T. Nucl. Sci., vol. 62, n. 3, 2015
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SLIDE 5
  • Jul. 2015

Fabio ACERBI - PhotoDet 2015

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SiPM SiPM te tech chno nolog logy y at at FB FBK

RGB SiPM NUV SiPM

SPAD size: 40mm Fill factor: 60% Peak PDE: 33% Max PDE @ 550nm ENF: ~1.7 DCR ~ 300 kHz SPAD size: 40mm Fill factor: 60% Peak PDE: 40% Max PDE @ 400nm ENF: ~1.5 DCR: < 100kHz

RGB-HD SiPM NUV-HD SiPM

Combine benefits of the HD technology (high FF & PDE, low correlated noise and high cell-density) with the advantages of p-on-n approach for detection at short wavelength

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SLIDE 6
  • Jul. 2015

Fabio ACERBI - PhotoDet 2015

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NUV NUV-HD HD SiPM SiPM te tech chno nolog logy

NU NUV SiPM SiPM NUV NUV-HD HD Si SiPM PM Trench

<2µm

  • Small cells

Gain reduction  afterpulsing and CT reduction

  • Redesigned border structure

Trenches between cells  Optical and electrical cell isolation Dead border reduction (< 2 µm)  increased FF

Small Cell Size without FF reduction

High-field region

Poly strip resistor

Metal

n- epi-Si n++ Substrate

High-field region

Cell 2 Cell 3 Cell 1

~4,5µm

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SLIDE 7
  • Jul. 2015

Fabio ACERBI - PhotoDet 2015

7

NUV NUV-HD HD SiPM SiPM te tech chno nolog logy

Trench < 1 um

  • Narrow trench, width < 1 um
  • High aspect ratio
  • Filled with silicon dioxide
  • Electrical and optical cell isolation

Cell Pitch = 15 µm

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SLIDE 8
  • Jul. 2015

Fabio ACERBI - PhotoDet 2015

8

  • 1. lower gain (lower Cd)  lower ENF
  • 1. afterpulsing reduction
  • 2. direct- and delayed-

Optical CT reduction

  • 3. external Optical CT

(with scintillator) reduction

  • 2. Larger dynamic range
  • 3. Faster recharge time
  • 1. reduced pile-up
  • 2. useful with «slow» scintillators (CsI) for further dynamic range

… but only if we have a high fill factor!!  need also high PDE

Small Small cells cells

substrate

active layer

  • +

external cross-talk

  • +

delayed cross-talk

+

scintillator

  • +

direct cross-talk

high-field region

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SLIDE 9

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

10 20 30 40 50 60 70

Fill factor Cell size (µm) 9

Devices with 4 different CS have been produced and tested !

NUV NUV-HD HD SiPMs SiPMs pr prot

  • tot
  • typ

ypes es

NUV SiPM (L=4.5µm)

NUV-HD (L<2µm) Cell Pitch FF Cell Density 15 µm 55 % ~4444 cells/mm2 20 μm 66 % 2500 cells/mm2 25 μm 73 % 1600 cells/mm2 30 μm 77 % ~1111 cells/mm2

  • Jul. 2015

Fabio ACERBI - PhotoDet 2015

Cell size

L

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SLIDE 10

Functional characterization

  • Jul. 2015

Fabio ACERBI - PhotoDet 2015

10

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SLIDE 11
  • Jul. 2015

Fabio ACERBI - PhotoDet 2015

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  • Reduced gain

~ 7·105 at 7V for 15µm cell (vs. ~4.5·106 of NUV SiPM)

  • Fast cell recharge  reduced pile-up

~ 20÷25 ns recharge time constant for 15µm cell

GAIN GAIN an and d rec recha harge rge-time time

Functional characterization

Also available SiPM with 15µm cell and halved Rq  lower recharge time

7V 7V

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SLIDE 12
  • Jul. 2015

Fabio ACERBI - PhotoDet 2015

12

  • PDE peaked in the blue region of the spectrum (~400nm):

– PDE >50% for 30µm cell, with 7V – PDE ~33% for 15µm cell, with 7V

Ph Photo

  • ton

n de detec tection tion efficie efficienc ncy y (PDE) (PDE)

30µm cell pitch PDE at 400nm

Functional characterization

7V

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SLIDE 13
  • Jul. 2015

Fabio ACERBI - PhotoDet 2015

13

  • Primary noise in the order of 100kcps/mm2

no increment due to trench and additional processes

  • Very Low afterpulsing + delayed CT

Only few percent at max excess bias (<1% for 15µm cell)

Noise Noise

Functional characterization

7V

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SLIDE 14
  • Jul. 2015

Fabio ACERBI - PhotoDet 2015

14

  • Prim. DCR of 100÷200 kcps/mm2

with PDE=50%

  • ENF <1.4 with PDE=50%

Comp Compariso arison a n as a fun s a functio ction o n of PDE f PDE

Functional characterization

PDE=50%

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SLIDE 15
  • Jul. 2015

Fabio ACERBI - PhotoDet 2015

15

NUV NUV-HD: HD: Lo Low w en ener ergy gy Ga Gamma mma 𝑒𝐹 𝐹 = 1 𝑂𝑡𝑑𝑗𝑜𝑢 ∙ 𝐹𝑂𝐺 𝑄𝐸𝐹 × 𝜁 + ⋯

LaBr

l = 400nm

ENF measured on SiPMs without scintillator NaI

Good results expected for energy resolution at 350nm÷450nm

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SLIDE 16
  • Jul. 2015

Fabio ACERBI - PhotoDet 2015

16

  • Minimum achieved CRTs are:

– ~100ps FWHM for the 5 mm crystal – ~150ps FWHM for the 22 mm crystal

NUV NUV-HD: HD: TOF TOF-PE PET T ap applica plicatio tion

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SLIDE 17
  • Jul. 2015

Fabio ACERBI - PhotoDet 2015

17

Co Conc nclusio lusions ns

  • HD technology was successfully applied to NUV SiPMs

investigating many SPAD sizes.

  • Very promising results:
  • PDE > 50%
  • Average DCR ~100 kcps/mm2
  • Low ENF (1.2÷1.4)
  • Fast recharge time-constant = few tens of ns
  • Very good time resolution with scintillator

& good energy resolution expected

Future Development

  • new technological features to further increase FF and

reduce the crosstalk

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SLIDE 18

High-Density-cell (HD) NUV Silicon Photomultipliers produced at FBK

  • F. Acerbi, A. Ferri, G. Zappalà,
  • A. Gola, G. Paternoster, N. Zorzi, C. Piemonte

http://iris.fbk.eu/silicon-photomultipliers http://srs.fbk.eu