G-APD radiation hardness D. Renker 1 , Y. Musienko 2, * 1) Paul - - PowerPoint PPT Presentation

LIGHT 07, September 26, 2007, Ringberg Castle G-APD radiation hardness 1

G-APD radiation hardness

• D. Renker1, Y. Musienko2,*

1)Paul Scherrer Institute, Villigen, Switzerland 2)Northeastern University, Boston, USA

*)on leave from INR(Moscow)

LIGHT 07, September 26, 2007, Ringberg Castle G-APD radiation hardness 2

Radiation damage in semiconductors ( Radiation damage in semiconductors (Si Si) )

Radiation damage in silicon is strongly Radiation damage in silicon is strongly dependent on the type and energy of the dependent on the type and energy of the radiation radiation Two types of radiation damage: Two types of radiation damage:

• Surface damage (ionizing damage in the

Surface damage (ionizing damage in the Si/SiO Si/SiO2

2 interface)

interface)

• Bulk damage (crystal lattice defects:

Bulk damage (crystal lattice defects: displacement of silicon atoms) displacement of silicon atoms)

LIGHT 07, September 26, 2007, Ringberg Castle G-APD radiation hardness 3

Surface damage Surface damage

SiO2 is a very good insulator (or a semiconductor with a large band gap of 8.8 eV). Electron/hole pairs created by ionizing particles can be trapped into very deep levels associated with the defects in oxide from which the emission back into conduction/valence band is very unlikely at room temperature Ionizing radiation (charged particles, gammas) produces surface damage (damage in the Si/SiO2 interface) due to accumulation

• f positive charges in the oxide (SiO2) and the Si/SiO2 interface

This may cause:

breakdown voltage shift (early APD breakdown) QE reduction surface current increase

LIGHT 07, September 26, 2007, Ringberg Castle G-APD radiation hardness 4

CMS APD irradiated with gammas from Co CMS APD irradiated with gammas from Co-

• 60

60 source source

Breakdown Voltage shift after 500 kRad (CMS APD)

• 30
• 25
• 20
• 15
• 10
• 5

5 8900 9000 9100 9200 9300 9400 9500 9600 APD # VB(irradiated)-VB(Hamamatsu) [V]

Rejected

Light is emitted from the point where the dielectric is broken by irradiation (HV is ON). (Picture is taken with the CCD camera at Hamamatsu)

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Bulk damage and NIEL function Bulk damage and NIEL function

Bulk damage scales linearly with the amount of Non Ionizing Energy Loss (NIEL hypothesis), which is very dependent on the particle type and its energy

NIEL(1 MeV gammas) ~ 10-5 * NIEL(1 MeV neutrons)

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Bulk damage effects Bulk damage effects

Increase of the dark current generated in the silicon bulk (multiplied current): Changes in the effective doping concentration (creation of acceptor-like states) a few weeks after irradiation:

Φeq – 1 MeV neutron equivalent total flux V – silicon active volume α – dark current damage constant (~4*10-17 A/cm for 1 MeV neutrons after 80 min annealing at 60 °C or ~10-16 A/cm after few days annealing at room temperature)

LIGHT 07, September 26, 2007, Ringberg Castle G-APD radiation hardness 7

Multipixel Geiger-mode APDs (G-APDs)

Model

Active G-APD volume: V= S*G*L=s*L S - total area s - active area (total area minus non-sensitive area between pixels) G - geometric factor L - depletion layer thickness Expected G-APD dark current increase after irradiation: ΔI=α∗M∗PG∗Φeq∗V α - dark current damage constant M – G-APD gain PG – Geiger discharge probability (is a f [V-VB]) Φeq – 1 MeV neutron equivalent total flux

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G G-

• APD radiation hardness studies

APD radiation hardness studies

G-APD’s radiation hardness was studied with:

28 MeV positrons (PSI)

• Hamamatsu MPPCs, CPTA/Photonique SSPMs, Dubna/Micron AMPDs

200 MeV protons (ITEP)

• MEPhI/Pulsar SiPMs

53.3 MeV protons (Osaka Univ.)

• Hamamatsu MPPCs

0.1-1 MeV neutrons (reactor (YAYOI))

• Hamamatsu MPPCs

290 MeV/nucleon C6+ ions (HIMAC)

• Hamamatsu MPPCs

Co60 ~1 MeV gammas (Tokyo Tech)

• Hamamatsu MPPCs

LIGHT 07, September 26, 2007, Ringberg Castle G-APD radiation hardness 9

28 28 MeV MeV positrons (PSI) positrons (PSI)

The reason we used 28 MeV positrons for APD irradiation:

• Excellent positron beam available at Paul Scherrer Institut (Villigen, Switzerland)
• Possibility to monitor and control beam intensity
• APDs are not activated during irradiation and measurements can be performed

immediately after irradiation

G-APDs and their parameters before irradiation (T=22 C)

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G-APDs spectral responses - measured at T=22 ºC

5 10 15 20 25 30 35 40 400 450 500 550 600 650 700 750 800

Wavelength [nm] PDE [%]

CPTA_t1, U=20.3 V CPTA_t2, U=52.5 V 2 4 6 8 10 12 14 16 18 20 350 400 450 500 550 600 650 700 750 800

Wavelength [nm] PDE [%] Dubna/Mikron_t1, U=119 V Dubna/Mikron_t2#1, U=26.3 V Dubna/Mikron_t3, U=45 V 5 10 15 20 25 30 35 40 350 400 450 500 550 600 650 700 750 800

Wavelength [nm] PDE [%]

Hamamatsu-t2, U=69.5 V Hamamatsu-t1, U=69.8 V

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Photon detection efficiency vs. bias voltage dependence (before and after 8*1010 positrons/cm2) measured at T=22 ºC

5 10 15 20 25 30 35 40 18 20 22 24 26 28

Bias [V] PDE(515 nm) [%]

before irr. after irr. CPTA-t1 Dubna/Mikron-t2#1 5 10 15 20 25 38 40 42 44 46 48 50 52 54 56

Bias [V] PDE(515 nm) [%]

before irr. after irr. CPTA-t2 Dubna/Mikron-t3 5 10 15 20 25 30 35 40 67 68 69 70 71

Bias [V] PDE(515 nm) [%]

before irr. after irr. Hamamatsu-t1 Hamamatsu-t2 5 10 15 20 25 116 117 118 119 120

Bias [V] PDE(515 nm) [%]

before irr. after irr. Dubna/Mikron-t1

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Gain vs. bias voltage dependence (before and after 8*1010 positrons/cm2) measured at T=22 ºC

0.01 0.1 1 10 18 20 22 24 26 28

Bias [V] Gain*106

before irr. after irr. CPTA-t1 Dubna/Mikron-t2#1

0.01 0.1 1 10 38 40 42 44 46 48 50 52 54 56

Bias [V] Gain*106

before irr. after irr. Dubna/Mikron-t3 CPTA-t2

0.01 0.1 1 10 67 68 69 70 71

Bias [V] Gain*106

before irr. after irr. Hamamatsu-t2 Hamamatsu-t1

0.01 0.1 116 117 118 119 120

Bias [V] Gain*106

before irr. after irr. Dubna/Mikron-t1

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Dark current vs. bias voltage dependence (before and after 8*1010 positrons/cm2) measured at T=22 ºC

0.1 1 10 100 18 20 22 24 26 28

Bias [V] Dark Current [μA]

before irr. after irr. CPTA-t1 Dubna/Mikron-t2#1 0.1 1 10 100 38 40 42 44 46 48 50 52 54 56

Bias [V] Dark Current [μA]

before irr. after irr. Dubna/Mikron-t3 CPTA-t2 0.001 0.01 0.1 1 10 100 67 68 69 70 71

Bias [V] Dark Current [μA]

before irr. after irr. Hamamatsu-t2 Hamamatsu-t1 0.01 0.1 1 116 117 118 119 120

Bias [V] Dark Current [μA]

before irr. after irr. Dubna/Mikron-t1

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Dark count rate vs. bias voltage dependence (before and after 8*1010 positrons/cm2) measured at T=22 ºC

5000 10000 15000 20000 25000 30000 18 20 22 24 26 28

Bias [V] Dark Count [kHz]

before irr. after irr. CPTA-t1 Dubna/Mikron-t2#1 5000 10000 15000 20000 25000 38 40 42 44 46 48 50 52 54 56

Bias [V] Dark Count [kHz]

before irr. after irr. Dubna/Mikron-t3 CPTA-t2 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 67 68 69 70 71

Bias [V] Dark Count [kHz]

before irr. after irr. Hamamatsu-t2 Hamamatsu-t1

1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 116 117 118 119 120

Bias [V] Dark Count [kHz]

before irr. after irr. Dubna/Mikron-t1

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Dark Count Increase/PDE/Area Dark Count Increase/PDE/Area

100 200 300 400 500 600 700 800 5 10 15 20 25 30 35

PDE(515 nm) [%] Dark Count Increase/PDE/Area [kHz/%/mm

2]

CPTA-t1 CPTA-t2 Hamamatsu-t1 Hamamatsu-t2 Dubna/Mikron-t1 Dubna/Mikron-t2#1 Dubna/Mikron-t2#2 Dubna/Mikron-t3

G-APDs studied have different area, geometric factor, depletion volume, etc. How to compare the dark count increase produced by radiation in different G-APDs? Expected G-APD dark count increase after irradiation: ΔN=ΔI/q/M=α*M*PG*Φeq*V/q/M=α*PG*Φeq*S*G*L/q, q – electron charge Assuming that PDE is proportional to PG *G: ΔN ~α*PDE*Φeq*S*L/q ΔN/PDE/S ~α*Φeq*L/q This ratio is expected to have weak dependence on the G-APD PDE, geometric factor and sensitive area. Dependence on the depletion thickness remains.

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Dark count damage constant (DCDC) Dark count damage constant (DCDC) evaluation evaluation

The ratio ΔN/PDE/S was found to be in the range of 70÷110 kHz/%/mm2 for 5 G-APDs out of 8 (see figure). For these G-APDs at T=22C: DCDC(28 MeV positrons)~0.9÷1.4*10-4 Hz/%/positron. NIEL factor for 28 MeV positrons is ~30 times smaller than for 1 MeV neutrons (this was verified by irradiating S8148 Hamamatsu APD with 28 MeV positrons and 1 MeV neutrons). One can calculate: DCDC(1 MeV neutrons)~2.7÷4.2*10-3 Hz/%/neutron This corresponds to the current ~ 4.3 ÷ 6.7*10-20 A/neutron (assuming PDE=100%). Such current will be produced in silicon bulk if we assume the thickness of the depletion layer in the range

• f 4 ÷ 7 μm and α~10-16 A/cm/neutron. This is somewhat higher

then the thickness of the epitaxial films used to produce G-APDs (~2-4 μm)

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200 200 MeV MeV protons (MEPHI/Pulsar protons (MEPHI/Pulsar SiPMs SiPMs) )

ΔI*M=4 μA after 1010 p/cm2 M ~106 , PDE(515nm) ~15%, S~1.2 mm2 NIEL(200 MeV protons)~ NIEL(1 MeV neutrons) L~25 μm? Too thick. No annealing?

M.Danilov arXiv:0704.3514v1

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53.3 53.3 MeV MeV protons ( protons (Hamamatsu Hamamatsu MPPC) MPPC)

ΔI*M~4 μA after 1010 p/cm2 M ~106 , PDE(515nm) ~30%, S=1 mm2 NIEL(53 MeV protons)~ 2*NIEL(1 MeV neutrons) L~6 μm (similar to the results with 28 MeV positrons) (From talk of T. Matsumura at PD-07) 0 Gy (27.6℃) 2.8 Gy (27.4℃) 5.5 Gy (27.2℃) 8.0 Gy (27.0℃)

Gain (106) bias voltage (-V)

Sample #21 16 Gy/h

• perating voltage

Vop = 69.58V

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Reactor neutrons Reactor neutrons

(From talk of T. Matsumura at PD-07)

ΔI*M~10 μA (V-VB~1.4V) after 1010 n/cm2 M ~2.5-3*106 , PDE(515nm) ~35%, S=1 mm2 L~4-5 μm (consistent with the results with 28 MeV positrons)

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1 1 MeV MeV gammas from Co gammas from Co-

• 60 source

60 source

(From talk of T. Matsubara at PD-07)

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MPPC damaged by gamma irradiation MPPC damaged by gamma irradiation

(From talk of T. Matsubara at PD-07)

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CMS APD damaged by 1 CMS APD damaged by 1 MeV MeV gammas gammas

Bias “ON” Bias “OFF” “Defect” is seen on all APD`s from the same position on the wafer - defect of the mask

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Summary Summary

Damage caused by ionizing radiation (60Co) should not be a real problem. A proper design of the cell edges and maybe a different crystal orientation will make the G-APD`s insensitive. Unavoidable defects on the surface might force a screening procedure. Displacement damage cannot be avoided. The dark count damage constant constant is (3.5±0.5)*10-3 Hz/%/neutron. Only a reduction of the contributing volume can keep the dark counts in a tolerable range.