Avalanche Photo-Diodes (APDs) K.Deiters, Q.Ingram, D.Renker, T.Sakhelashvili
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Transcript of Avalanche Photo-Diodes (APDs) K.Deiters, Q.Ingram, D.Renker, T.Sakhelashvili
APD MPR July 24th 2002 D. Renker PSI 1
Avalanche Photo-Diodes (APDs)
K.Deiters, Q.Ingram, D.Renker, T.SakhelashviliPaul Scherrer Institute, Villigen, Switzerland
J.Grahl, I.Kronqvist, R.Rusack, A.Singovski, P.VikasUniversity of Minnesota, Minneapolis, USA
I.Britvitch, A.Kuznetsov, Y.Musienko, S.Reucroft, J.SwainNortheastern University, Boston, USA
Z.Antunovic, N.Godinovic, I.SoricUniversity of Split, Croatia
Honorary assistent: J-L.Faure
2D. Renker PSIAPD MPR July 24th 2002
APD History
Late 1992: 1st Hamamatsu prototype
Early 90th Push for a homogeneous calorimeter
1995: Test of an APD on a PbWO4 crystal in H4
1996-97: APDs chosen for ECAL
A comparison of the response to 80 GeV electrons of a lead tungstate crystal with a PIN diode (top) and an APD (bottom) read-out. The tail to the right of the peak in the PIN diode spectrum is due to particles leaking out of the back of the 18 cm long crystal and passing through the diode
APD MPR July 24th 2002 D. Renker PSI 3
APD propertiesAPD properties
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Quantum Efficiency [%]
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Voltage [V]
Gain
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1/M*dM/dV [%]
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1/M*dM/dT [%]
APD MPR July 24th 2002 D. Renker PSI 4
APD properties cont. (1)APD properties cont. (1)
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Gain
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Voltage [V]
Capacitance [pF]
APDs are insensitive to magnetic fields, are compact, cheap and have a small nuclear counter effect. They are potentially radiation hard.
But: they have a small area (5x5 mm2) and they were a widely unknown device
APD MPR July 24th 2002 D. Renker PSI 5
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ProductionPrototypes
Error bar shows range within delivery
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Frequency
Stable since 2000
Distance of operating to breakdown voltageDistance of operating to breakdown voltage
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Side remark: Thousands of APDs have been tested and sometimes “accidents” happened. APDs were biased with the wrong polarity for a long period or the bias voltage was far too high (3000 V instead of 300 V). No APD ever died due to such an event.
APD MPR July 24th 2002 D. Renker PSI 6
Reliability testsReliability tests
Weak or bad APDs are identified by a number of tests after the 60Co irradiation:
is there a change of the breakdown voltage (dVb)? is the dark current at gain 50 within the limits (Id)? Is the dark current divided by the gain falling continuously (Id/M vs M)? Is there an abnormal high noise? Is the APD coming from a “bad position” on the wafer (mask problem)? Is the APD coming from a “bad wafer” (problem in the neutron irradiation)?
The same tests are performed after the annealing with the exception of the noise. The noise is later on measured in Lyon when the APDs have been mounted on the capsule.
How do we measure these parameters? Yuri
How efficient is the screening? Quentin
What are the rejection criteria? Sasha
APD MPR July 24th 2002 D. Renker PSI 7
PROVISIONAL FINAL TECHNICAL SPECIFICATIONPROVISIONAL FINAL TECHNICAL SPECIFICATION
General conditions: VR (operating voltage for gain M = 50) and VB (breakdown voltage, at which the dark current exceeds 100 A), asall other values measured at T = 25 C. For radiation hardness: neutron (1 MeV) fluence 2x1013 n/cm2
Sensitive area 5x5 mm2
Survival rate after irradiation * 99.9 0.1 %Survival rate after 2 months at 90º C @ M=50 * 99.9 0.1 %
Survival rate after 1 day at 20 A (V = VB + 20V) (1) * 99.9 0.1 %
Passivation layer Si3N4
Charge collection within 20 ns (2) 99 1 %
Capacity at VR (mean value) 65 – 85 pF
Spread of capacity at VR 5 pF
Capacity at VR – Capacity at VB 3 pF
DM/dV·1/M (gain sensitivity to voltage) at VR 3.5 %/VQuantum efficiency (mean value) (3) 75 5 % @ 430 nmSpread of measured quantum efficiency (3) 7 %
Operating voltage VR 340 – 440 V
Difference VB - VR ** 37 V
Nuclear counter effect leff (4) < 7 m
Excess noise factor at VR 2 0.3 @ 430 nm
Dark current Id at VR 50 nASerial resistance (mean value) < 5 Spread of serial resistance 1 DM/dT·1/M (gain sensitivity to temperature) at VR 2 0.5 %/deg CelsiusRatio of Noise (M=300)/Noise (M=50) (5) 12Variation of Id/gain for 50 < M < 400 (6) < 10% rise Change of QE after irradiation 2 %Change of gain after irradiation (7) 3 % Dark current (bulk) after irradiation (7) 5 A
Spread of Id (total) at VR after irradiation (7) 0.5 A
Difference VB-VR after irradiation (7) > 30 V