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

INSTR-08, Novosibirsk, 3.03.2008 Y. Musienko ([email protected]) 1

Advances in multi-pixel Geiger mode

APDs (Silicon Photomultipliers).

Yuri Musienko

Northeastern University, Boston

&

INR, Moscow


Outline

• SiPM: principle of operation

• SiPM parameters, important for HEP

applications

• New developments

• Radiation hardness

• Summary


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. (1963-1965))

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 mm2 Geiger mode APD can

operate only at low temperature, needs “active quenching”)

Solution: Multipixel Geiger mode APD (MPGM APD)


First design (MRS APD, 1989) Few % photon detection efficiency for red light was measured with 0.5x0.5 mm2 APD. Good pixel-to-pixel uniformity. Small geometrical efficiency. Very low QE for green and blue light.

LED pulse spectrum(A. Akindinov et al., NIM387 (1997) 231)

The very first metall-resitor-smiconductor APD (MRS APD) proposed

by A. Gasanov, V. Golovin, Z. Sadygov, N. Yusipov (Russian patent

#1702881, from 10/11/1989 ). APDs up to 5x5 mm2 were produced by

MELZ factory (Moscow).


Developers and producersSince 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 …


Structure and principles of

operation

Picture from talk of E. Grigoriev at Como 2001

• Geiger avalanche is quenched by an individual pixel resistor (from 100kΩ to several MΩ).

• It contains 100 20 000 pixels/mm2 , made on common substrate and connected together

• Each pixel works as a binary device

• MGAPD is pixellated silicon avalanche photodiode operated in Geiger mode (~10-20% over breakdown voltage)

• For small light pulses (Ng<<Npixels) device as a whole works as an analog detector


SiPMs pixel-to-pixel uniformity

Green-red light sensitive APD, low amplitude

light signals, U=43V, T=-28 C

0

500

1000

1500

2000

0 500 1000 1500 2000

ADC ch#

Co

un

ts

MPGM APDs/SiPMs have very good pixel-to-pixel signal uniformity. Pedestal is

well separated from the signal produced by single fired pixel Q1 .


Parameter definition: Gain

Each pixel works as a digital device – 1,2,3... photons produce the same

signal Q1=Cpixel*(V-Vb) (or Single Pixel Charge).

Multi-pixel structure works as a linear device, as soon as Npe=Ng*QE<<N0

, N0 – is a total number of pixels/device

Measured charge :

Qoutput=Npe*Gain ,

It was found by many groups that : Gain ≠ Q1 ,

More than 1 pixel is fired by one primary photoelectron!

Gain=Q1*np ,

where np 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)


Gain and Single Pixel Charge

)(1 Bpix VVCQ

fired

pixelsNQM 1


Photon detection efficiency

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 Pb (depends on the V-Vb !!, Vb – is a breakdown

voltage) .

PDE (l, U,T) = QE(l)*Gf*Pb(U,T)

0

5

10

15

50 55 60 65

PD

E(5

15

nm

) [%

]

Bias [V]

MEPhI/PULSAR APD

T= 22 C

T=-28 C

MEPhI/PULSAR APD, U=57.5 V, T=-28C

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 200 400 600 800 1000ADC, ch.

Co

un

tsTo determine <Npe> in light pulse one can use well known property of the Poisson distribution :

<Npe> = - ln(P(0))

Average number of photons <Ng> in LED pulse can be measured using calibrated photo-sensor . Then:

PDE(l) = <Npe>/ <Ng>


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


Geometric factor


Structure for green/red light

B. Dolgoshein et. al., “An advanced study of

silicon photomultiplier”, ICFA-2001

MEPhI/PULSAR APD, T=22C, U=59 V

0

2

4

6

8

10

12

400 450 500 550 600 650 700 750 800

Wavelength [nm]

PD

E [

%]

(Y. Musienko, Beaune-05)

0

10

20

30

40

50

60

350 400 450 500 550 600 650 700 750 800

PD

E [

%]

Wavelength [nm]

T=22 CCPTA/Photonique APD

(Y. Musienko, PD-07, Kobe)

Absorption length for light in silicon


Improved blue sensitivity

Shallow-Junction SiPM

13

14

15

16

17

18

19

20

0 0.2 0.4 0.6 0.8 1 1.2 1.4

depth (um)

Do

pin

g c

on

c. (1

0^

) [1

/cm

^3

]

0E+00

1E+05

2E+05

3E+05

4E+05

5E+05

6E+05

7E+05

E f

ield

(V

/cm

)

Doping

Field

n+ p

(G. Pauletta: PD07, Kobe, Japan)0.00E+00

2.00E+00

4.00E+00

6.00E+00

8.00E+00

1.00E+01

1.20E+01

1.40E+01

1.60E+01

350 400 450 500 550 600 650 700 750 800

Wavelength (nm)

PD

E (

%)

36V

36.5V

37V

37.5V

38V

DV=2V

2.5V

3.5V3V

4V

To improve sensitivity for blue/UV light structure with shallow junction (~100 nm) was produced


Blue sensitive G-APD

p＋

p－-epi

n＋＋-subst.

K.Yamamoto, PD-07, Kobe

(optical crosstalk and after-pulses were not

taken into account)

0

5

10

15

20

25

30

35

350 400 450 500 550 600 650 700 750 800

PD

E [

%]

Wavelength [nm]

T=22 C HPK S10362-11-050C

(Y. Musienko, PD-07, Kobe)

Measured using t technique described in

NIMA 567 (2006) 57

Another solution: “reversed” APD structure. In “reversed”

structure electrons initiate the avalanche breakdown


Optical cross-talk

Hot-carrier luminescence:

105 carriers produces ~3 photons with

an wavelength less than 1 mm

Increases with the gain !

Solution: optically separate pixels with grooves

Optical cross-talk causes adjacent pixels to be fired increases gain

fluctuations increases noise and excess noise factor !


Single electron spectrum

SES CPTA APD, U=42 V, T=-28 C

1

10

100

1000

10000

200 300 400 500 600 700

ADC ch.

Co

un

ts

When V-Vb>>1 V typical single pixel signal resolution is better than 10%

(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

10

100

1000

10000

0 100 200 300 400 500

ADC ch.

Co

un

ts


Excess Noise Factor

MEPhI/PULSAR APD

0

0.5

1

1.5

2

2.5

3

0 0.5 1 1.5 2 2.5 3Single Pixel Charge*106

Nu

mb

er

of

fire

d

pix

els

T= 22 C

T=-28 C

2

2

1M

F M

… and in an increase of the SiPM excess noise factor


The dark rate of the SiPM for different gains in

dependence on the level of the threshold

0 2 4 6 8 10 12 14 1610

-1

100

101

102

103

104

105

106

dark

rate

, H

z

Threshold, pixels

gain 7*105

gain 1*106

gain 1.3*106

Optical cross-talk increases

the dark count at high

electronics thresholds

(E.Popova, CALICE meeting)


Gain is voltage and temperature

dependent

MEPhI/PULSAR APD

0

2

4

6

8

50 55 60 65Bias [V]

Gain

*106

T= 22 C

T=-28 C

MEPhI/PULSAR APD

0

0.5

1

1.5

2

2.5

3

50 55 60 65Bias [V]

Sin

gle

Pix

el

Ch

arg

e*1

06 T= 22 C

T=-28 C

MEPhI/PULSAR APD

0

0.5

1

1.5

2

2.5

3

0 0.5 1 1.5 2 2.5 3Single Pixel Charge*106

Nu

mb

er o

f fi

red

pix

els

T= 22 C

T=-28 C

SiPM gain and PDE are temperature dependent


Response temperature

sensitivityCPTA APD

0

50

100

150

200

250

300

350

400

30 32 34 36 38 40 42 44

Bias [V]

Sig

na

l a

mp

litu

de

[A

DC

ch

.]

T=-25 C

T= 22 C

Hamamatsu MPPC

0

20

40

60

80

100

120

140

160

180

200

66.5 67 67.5 68 68.5 69 69.5 70 70.5 71

Bias [V]

Am

plitu

de [

AD

C c

h.]

T=-25 C

T= 22 C

CPTA/Photnique:

dVB/dT=-20 mV/C

Hamamatsu:

dVB/dT=-50 mV/C

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)


Temperature coefficient

CPTA APD

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

34 35 36 37 38 39 40 41 42 43

Bias [V]

-1/A

*dA

/dT

[%

]

S10362-11-050C HPK MPPC

0

2

4

6

8

10

12

14

16

69 69.2 69.4 69.6 69.8 70 70.2 70.4 70.6

Bias [V]

-1/A

*dA

/dT

[%

]

kT=dA/dT*1/A, [%/C]


Optical cross-talk reduction

To reduce optical cross-talk CPTA was the first to introduce trenches separating the neighbouring pixels (E. Grigoriev Como 2001)


SiPMs with reduced optical

cross-talkSiPM with trenchesSiPM without trenches

MEPhI/PULSAR APD

0

0.5

1

1.5

2

2.5

50 55 60 65Bias [V]

Exce

ss N

oise

Fac

tor T= 22 C

T=-28 C

CPTA APD

0.9

0.95

1

1.05

1.1

1.15

1.2

30 32 34 36 38 40 42 44

Bias [V]

F


The dark rate of the SiPM trenches in

dependence on the discriminator threshold

0.1

1

10

100

1000

10000

0 1 2 3

Dark

Co

un

t [k

Hz]

Threshold [fired pixels]

36V

33 V

CPTA/Photonique SSPM with trenches


SiPM timing

Measured with MEPhI/Pulsar

SiPM using single photons (B.

Dolgoshein, Beaune-02)

SiPMs have excellent timing properties

Measured with 100 mm SPAD

using single photons


Linearity

(B. Dolgoshein, TRD05, Bari)

This equation is correct for

light pulses which are shorter

than pixel recovery time , and

for an “ideal” SiPM (no cross-

talk and no after-pulsing)

Linearity of SiPM is determined by its total number of pixels

In the case of uniform illumination:


Micro-pixel APDs with large

dynamic range

Z. Sadygov, Beaune-05

M.Golubeva et.al. LONGITUDINALLY SEGMENTED

LEAD/SCINTILLATOR HADRON CALORIMETER WITH

MICROPIXEL APD READOUT (this conference)

Micro-well structure with multiplication

regions located in front of wells at 2-3 mm

depth was developed by Z. Sadygov.

MAPDs with 10 000 – 15 000 pixels/mm2

were produced. Such devices are good for

calorimetry applications.


After-pulsing

Solution: “cleaner” technology or longer pixel recovery time

-0.35

-0.3

-0.25

-0.2

-0.15

-0.1

-0.05

0

0.05

-1.0E-08 1.0E-08 3.0E-08 5.0E-08 7.0E-08

Time (s)

Vo

lta

ge

(V

)

Events with after-pulse measured on a

single micropixel.

y = 0.0067x2 - 0.4218x + 6.639

y = 0.0068x2 - 0.4259x + 6.705

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

31 32 33 34 35 36

Voltage (V)

Afte

rpu

lse

/pu

lse

Tint = 60ns

Tint = 100ns

After-pulse probability vs bias

C. Piemonte: June 13th, 2007, Perugia


Large area SiPMs

1x1mm 2x2mm 3x3mm (3600 cells) 4x4mm (6400 cells)

FBK-irst SiPMs, C. Piemonte: June 13th, 2007, Perugia

SiPMs with up to 3x3 mm2 area produced by many companies: Hamamatsu,

CPTA/Photonique, Pulsar, Zecotek, SensL, FBK-irst


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


Radiation damage of MPPCs using

gammas from Co60

Matsubara, PD-07, Kobe

Infrared emission (similar

effects were seen with

irradiated “linear” APDs


Radiation damage of SiPMs using protons

200 MeV protons, M.Danilov

arXiv:0704.3514v1

Protons like 1 MeV neutrons produce

defects inside silicon.

Increase of the dark current:

Id~a*F*V*M*k,

a – dark current damage constant [A/cm];

F – particle flux [1/cm2];

V – silicon active volume [cm3]

M – SiPM gain

k – NIEL coefficient


Irradiation studies at PSI (82 MeV protons)

• 23 SiPMs from 4 different producers irradiated at PSI last week

• 1*1010 400 MeV/c (82 MeV kinetic energy) protons/cm2 in 4 steps

•NIEL factor is ~2 times of 1 MeV neutrons, Total flux: 1*1010 protons/cm2, equivalent to ~2*1010 1 MeV neutrons/cm2

Gain, PDE, Id, Dark count vs. voltage were measured before irradiation

0

2

4

6

8

10

12

0 1 2 3 4 5

Dar

k C

urr

en

t [m

kA]

Irradiation #

"HPK_1mm_#535" (U=69.5V)

"HPK_1mm_#535"(U=70.1V)

"HPK_1mm_#535"(U=70.7V)

CPTA#3

0

5

10

15

20

25

30

30.5 31 31.5 32 32.5 33 33.5 34 34.5

Bias [V]

PD

E(5

15n

m)

[%]

before irr.

after irr.

FBK_K1

0

5

10

15

20

25

30

31 31.5 32 32.5 33 33.5 34 34.5

Bias [V]

PD

E(5

15n

m)

[%]

before irr.

after irr.

Hamamatsu #534

0

5

10

15

20

25

30

69 69.2 69.4 69.6 69.8 70 70.2

Bias [V]

PD

E(5

15

nm

) [%

]

before irr.

after irr.

Actve area of SiPMs ~1 mm2


Dark Count vs. bias 2 month after irradiationHamamatsu #534

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

69 69.2 69.4 69.6 69.8 70 70.2

Bias [V]

Da

rk C

ou

nt

[kH

z] before irr.

after irr.

FBK_K1

0

5000

10000

15000

20000

25000

30000

35000

40000

31 31.5 32 32.5 33 33.5 34 34.5

Bias [V]

Da

rk C

ou

nt

[kH

z]

before irr.

after irr.

CPTA#3

0

5000

10000

15000

20000

25000

30000

35000

40000

30.5 31 31.5 32 32.5 33 33.5 34 34.5

Bias [V]

Dark

Co

un

t [k

Hz]

before irr.

after irr.

Dark count increase

0

200

400

600

800

1000

1200

1400

1600

0 5 10 15 20 25 30

PDE(515nm)

Da

rk C

ou

nt/

PD

E(5

15n

m) CPTA#3

FBK_K1

Hamamatsu #534

0

5

10

15

20

25

0 10 20 30Eff

ec

tive

Th

ick

nes

s [

mm

]

PDE(515nm)

Effective thickness (aSi= 4*10-17 A/cm)

CPTA#3

FBK_K1

Hamamatsu #534


Summary

Significant progress in development of SiPMs during recent 2-3 years:

• High PDE~30-40% for blue-green light (CPTA/Photonique, Hamamatsu)

• Reduction of dark count at room temperature (~100-300 kHz, Hamamastu)

• Low cross-talk (<5-10%, CPTA/Photonique, FBK)

• Low temperature coefficient (~0.3%/C, CPTA/Photonique)

• Fast timing (~50 ps (RMS) for single photons)

• Large dynamic range (10 000 – 15 000 pixels/mm2, Dubna/Zecotek)

• Large area (3x3 mm2, 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…)

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

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