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

G-APD radiation hardness D. Renker 1 , Y. Musienko 2, * 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 1

Radiation damage in semiconductors (Si Si) ) Radiation damage in semiconductors ( 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 2 interface) Si/SiO 2 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 2

Surface damage Surface damage SiO 2 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 of 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 3

CMS APD irradiated with gammas from Co- -60 60 CMS APD irradiated with gammas from Co source source Breakdown Voltage shift after 500 kRad (CMS APD) 5 VB(irradiated)-VB(Hamamatsu) [V] 0 -5 -10 -15 Rejected -20 -25 -30 8900 9000 9100 9200 9300 9400 9500 9600 APD # 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) LIGHT 07, September 26, 2007, Ringberg Castle G-APD radiation hardness 4

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) LIGHT 07, September 26, 2007, Ringberg Castle G-APD radiation hardness 5

Bulk damage effects Bulk damage effects Increase of the dark current generated in the silicon bulk (multiplied current): Φ eq – 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) Changes in the effective doping concentration (creation of acceptor-like states) a few weeks after irradiation: LIGHT 07, September 26, 2007, Ringberg Castle G-APD radiation hardness 6

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: Δ I= α∗ M ∗ P G ∗Φ eq ∗ V α - dark current damage constant M – G-APD gain P G – Geiger discharge probability (is a f [V-VB]) Φ eq – 1 MeV neutron equivalent total flux LIGHT 07, September 26, 2007, Ringberg Castle G-APD radiation hardness 7

G- -APD radiation hardness studies APD radiation hardness studies G 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 • Co 60 ~1 MeV gammas (Tokyo Tech) Hamamatsu MPPCs • LIGHT 07, September 26, 2007, Ringberg Castle G-APD radiation hardness 8

28 MeV MeV positrons (PSI) positrons (PSI) 28 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) LIGHT 07, September 26, 2007, Ringberg Castle G-APD radiation hardness 9

G-APDs spectral responses - measured at T=22 ºC 40 20 CPTA_t1, U=20.3 V 35 18 CPTA_t2, U=52.5 V 16 30 14 25 PDE [%] 12 PDE [%] 20 10 15 8 Dubna/Mikron_t1, U=119 V Dubna/Mikron_t2#1, U=26.3 V 10 6 Dubna/Mikron_t3, U=45 V 4 5 2 0 0 400 450 500 550 600 650 700 750 800 350 400 450 500 550 600 650 700 750 800 Wavelength [nm] Wavelength [nm] 40 Hamamatsu-t2, U=69.5 V 35 Hamamatsu-t1, U=69.8 V 30 25 PDE [%] 20 15 10 5 0 350 400 450 500 550 600 650 700 750 800 Wavelength [nm] LIGHT 07, September 26, 2007, Ringberg Castle G-APD radiation hardness 10

Photon detection efficiency vs. bias voltage dependence (before and after 8*10 10 positrons/cm 2 ) measured at T=22 ºC 40 25 before irr. before irr. after irr. 35 CPTA-t1 after irr. 20 30 PDE(515 nm) [%] PDE(515 nm) [%] CPTA-t2 Dubna/Mikron-t3 25 Dubna/Mikron-t2#1 15 20 10 15 10 5 5 0 0 18 20 22 24 26 28 38 40 42 44 46 48 50 52 54 56 Bias [V] Bias [V] 40 25 before irr. before irr. after irr. after irr. 35 Dubna/Mikron-t1 Hamamatsu-t2 20 30 PDE(515 nm) [%] PDE(515 nm) [%] 25 15 20 10 15 10 5 Hamamatsu-t1 5 0 0 67 68 69 70 71 116 117 118 119 120 Bias [V] Bias [V] LIGHT 07, September 26, 2007, Ringberg Castle G-APD radiation hardness 11

Gain vs. bias voltage dependence (before and after 8*10 10 positrons/cm 2 ) measured at T=22 ºC 10 10 before irr. before irr. after irr. after irr. Dubna/Mikron-t3 CPTA-t2 Dubna/Mikron-t2#1 1 1 Gain*10 6 Gain*10 6 CPTA-t1 0.1 0.1 0.01 0.01 18 20 22 24 26 28 38 40 42 44 46 48 50 52 54 56 Bias [V] Bias [V] 10 0.1 before irr. before irr. after irr. after irr. Hamamatsu-t2 Dubna/Mikron-t1 1 Gain*10 6 Gain*10 6 Hamamatsu-t1 0.1 0.01 0.01 67 68 69 70 71 116 117 118 119 120 Bias [V] Bias [V] LIGHT 07, September 26, 2007, Ringberg Castle G-APD radiation hardness 12

Dark current vs. bias voltage dependence (before and after 8*10 10 positrons/cm 2 ) measured at T=22 ºC 100 before irr. 100 before irr. CPTA-t1 after irr. after irr. CPTA-t2 Dubna/Mikron-t2#1 Dark Current [ μ A] Dark Current [ μ A] 10 10 Dubna/Mikron-t3 1 1 0.1 0.1 18 20 22 24 26 28 38 40 42 44 46 48 50 52 54 56 Bias [V] Bias [V] 100 1 before irr. before irr. after irr. after irr. Hamamatsu-t2 Dubna/Mikron-t1 10 Dark Current [ μ A] Dark Current [ μ A] 1 0.1 0.1 Hamamatsu-t1 0.01 0.001 0.01 67 68 69 70 71 116 117 118 119 120 Bias [V] Bias [V] LIGHT 07, September 26, 2007, Ringberg Castle G-APD radiation hardness 13

Dark count rate vs. bias voltage dependence (before and after 8*10 10 positrons/cm 2 ) measured at T=22 ºC before irr. before irr. 30000 25000 after irr. after irr. CPTA-t1 CPTA-t2 25000 20000 Dark Count [kHz] Dark Count [kHz] 20000 15000 Dubna/Mikron-t2#1 15000 Dubna/Mikron-t3 10000 10000 5000 5000 0 0 18 20 22 24 26 28 38 40 42 44 46 48 50 52 54 56 Bias [V] Bias [V] before irr. 10000 before irr. 10000 after irr. after irr. 9000 9000 Dubna/Mikron-t1 8000 8000 Dark Count [kHz] Dark Count [kHz] Hamamatsu-t2 7000 7000 6000 6000 5000 5000 Hamamatsu-t1 4000 4000 3000 3000 2000 2000 1000 1000 0 0 116 117 118 119 120 67 68 69 70 71 Bias [V] Bias [V] LIGHT 07, September 26, 2007, Ringberg Castle G-APD radiation hardness 14

Dark Count Increase/PDE/Area Dark Count Increase/PDE/Area 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: Δ N= Δ I/q/M= α *M*P G * Φ eq *V/q/M= α *P G * Φ eq *S*G*L/q, q – electron charge Assuming that PDE is proportional to P G *G: Δ N ~ α *PDE* Φ eq *S*L/q � Δ N/PDE/S ~ α * Φ eq *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. 800 CPTA-t1 CPTA-t2 Dark Count Increase/PDE/Area 700 Hamamatsu-t1 Hamamatsu-t2 600 Dubna/Mikron-t1 2 ] Dubna/Mikron-t2#1 500 [kHz/%/mm Dubna/Mikron-t2#2 400 Dubna/Mikron-t3 300 200 100 0 0 5 10 15 20 25 30 35 PDE(515 nm) [%] LIGHT 07, September 26, 2007, Ringberg Castle G-APD radiation hardness 15