A Feasibility Study of a Single Event Spectrometer Based on Semiconductor Devices
S. Agosteo(1), A. Castoldi(1), L. Castellani (3), P. Colautti(2), G. D’Angelo(1), L. De Nardo(3), A. Favalli(1), I. Lippi(3),
R. Martinelli(3), G. Tornielli(3), P. Zotto(4).
(1) Dipartimento di Ingegneria Nucleare, Politecnico di Milano, via Ponzio 34/3, 20133 Milano, Italy and INFN, Sezione di Milano, via Celoria 16, 20133 Milano, Italy, e-mail: [email protected].
(2) INFN, Laboratori Nazionali di Legnaro, via Romea 4, 35020 Legnaro, Italy.
(3) Dipartimento di Fisica, Università di Padova and INFN, Sezione di Padova, via Marzolo 8, 35131 Padova, Italy.
(4) Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32,
20133 Milano, Italy and INFN, Sezione di Padova, via Marzolo 8, 35131
Single Event Effect Phenomenology
• Single Events are due to the interaction of a neutron with the silicon atoms releasing locally a large amount of
energy:
– Single Event Upset (SEU): Modification of a memory state;
– Latch-up: integrated circuit block recoverable by reset;
– Gate rupture (destructive);
– Device burn-out (destructive);
– Transient (noise signal in charge-sensitive devices).
Relevant Physics Processes
• Thermal Neutrons:
10 B(n, α ) 7 Li
(boron is a common dopant)
• Fast neutrons:
28 Si(n, α ) 25 Mg (Threshold E n =2.7 MeV)
28 Si(n,p) 28 Al (Threshold E n =4.0 MeV) etc.
• Inelastic scattering open at a certain threshold
SEU measurements on SRAMs
Thermal neutrons Fast neutrons from
9Be(d,n)
10B
A SEU spectrometer
• Try to measure the energy spectrum and the lineal-energy distribution of charged particles induced by neutron on silicon devices (at the LNL, Italy);
• Use a windowless p-i-n photodiode 200 µ m thick
not biased (V bias =0 V depletion layer 20 µ m thick) (Hamamatsu S3590-02):
– bare for SEE measurements;
– covered with TE plastic for microdosimetric applications;
– covered with a hydrogenated radiator for fast neutron
Spectrum of charged particles from thermal neutrons
• Thermal neutrons generated via the 9 Be(d,n) 10 B reaction (thick target + moderator);
• Several deuteron energies.
103 104
0.00 0.01 0.02 0.03 0.04 0.05
n + 10B ----> 7Li + α (Q =2.31 Me V)
2.3 MeV - 7Li+α
1.5 MeV -α 0.8 MeV - 7Li
In the cavity of the thermal neutron facilit9Be(d,n)y - 10B
E
d=3.0 MeV E
d=4.5 MeV E
d=6.5 MeV
E*f(E)
E (keV)
Spectrum of charged particles from fast neutrons
• Monoenergetic neutrons from the 7 Li(p,n) 7 Be reaction;
• High LET particles are observed only above threshold.
1000 10000
0.000 0.002 0.004 0.006 0.008 0.010 0.012 0.014 0.016 0.018
0.020 LiF monoenergetic neutrons - bare p-i-n photodiode
E
n=0.996 Me V @0 ¡ E
n=4.536 Me V @0 ¡
E*f(E)
E (ke V)
Measurements for microdosimetry applications
• Photodiode covered with TE plastic. Irradiation with monoenergetic neutrons;
• R
prange of recoil protons in silicon – Depletion layer thickness @ V
bias= 0 V: 20 µm
• Peak shift associated to charged collection from substrate
10 100 1000
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
En=0.996 Me V @ 0¡ - R
p=16 µm En=2.019 Me V @ 0¡ - R
p=50 µm En=4.536 Me V @ 0¡ - R
p=185 µm LiF mo noenergetic neutrons - with TE plastic
y*d(y)
y ( keV
µm
-1)
Measurements for fast neutron spectrometry (recoil protons)
• Photodiode covered with a hydrogenated radiator;
• Photodiode calibrated with α -particles from a nat U source;
• Irradiation with monoenergetic neutrons.
0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 10-7
10-6 1x10-5 1x10-4
10-3 LiF monoenergetic neutrons @ 0¡
w ith polyethylene Vbias=0 V
En=0.573 MeV En=0.680 MeV En=0.734 MeV En=0.787 MeV En=0.892 MeV En=0.996 MeV En=1.100 MeV En=1.203 MeV En=1.306 MeV En=1.511 MeV En=1.715 MeV En=1.918 MeV En=2.323 MeV
Response (cm
2 )
