SOLID STATE NEUTRON DETECTOR

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S. AMELINCKX (C.E.N.), R. DE CONINCK (C.E.N.),
M. DENAYER (C.E.N.), A. GIJS (C.E.N.),
M. HEERSCHAP (EURATOM), P. NAGELS (C.E.N.),
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H/UNITED STATES AGREEMENT FOR COOPERATION
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EURAEC Report No 587 established by the
Centre d'Etude de l'Energie Nucléaire C.E.N., Mol (Belgium)
MfcwSBSÊL
Euratom Contract No 079-61-10 RDB HËjÈ "**privaldy owned rishts: lilSiPlieilliP^i
- Assume any liability with respect to the use of, or for damages resulting from the use of
any information, apparatus, method or process disclosed in this document.
"MM ' EUR 431.e
SOLID STATE NEUTRON DETECTOR by S. AMELINCKX,
R DE CONINCK, M. DENAYER, A. GIJS (C.E.N.). M. HEERSCHAP
(EURATOM), P. NAGELS and L. VAN GOOL .
European Atomic Energy Community ­ EURATOM.
EURATOM/UNITED STATES Agreement for Cooperation.
EURAEC Report No 587 established by the Centre d'Etude de l'Energie
Nucléaire, C.E.N., Mol (Belgium).
Euratom Contract No 079­61­10 RDB.
Brussels, November 1964, page 57 ­ figure 36.
The object of this research program is to develop a neutron detector for the
detection of high neutron fluxes at high temperatures thereby using the SiC
diodes.
A number of grown SiC p­i­n junctions, obtained from the Philips Research
Laboratories, have been irradiated in the BRI reactor. The change of their
electrical characteristics and of the short­circuit photo­current can be explained
by assuming that the intrinsic region, which is slightly p­doped before irradia­
tion becomes slightly η­doped upon prolonged irradiation, hereby reaching a
EUR 431.e
SOLID STATE NEUTRON DETECTOR by S. AMELINCKX,
R DECONINCK, M. DENAYER, A. GIJS(C.Ë.N.), M. HEERSCHAP
(EURATOM), P. NAGELS and L. VAN GOOL (C.E.N.).
European Atomic Energv Community ­ EURATOM.
EURATOM/UNITED STATES Agreement for Cooperation.
EURAEC Report No 587 established by the Centre d'Etude de l'Energie
Nucléaire, C.E.N., Mol (Belgium).
Euratom Contract No 079­61­10 RDB.
Brussels, November 1964, page 57 ­ figure 36.
The object of this research program is to develop a neutron detector for the
detection of high neutron fluxes at high temperatures thereby using the SiC
diodes.
A number of grown SiC p­i­n junctions, obtained from the Philips Research
Laboratories, have been irradiated in the BRI reactor. The change of their
electrical characteristics and of the short­circuit photo­current can be explained
by assuming that the intrinsic region, which is slightly p­doped before irradia­
tion becomes slightly η­doped upon prolonged irradiation, hereby reaching a relatively low limiting value of electron concentration. This would correspond
to a shift of the Fermi-level of the intrinsic region to a position in the lower
part of the upper half of the forbidden energy gap. Not much annealing is found
on measuring the change of the electrical characteristics upon pulse annealing.
Because of the smallness of the width of the space-charge layer (about 1
micron), the grown SiC diodes could not be used as detectors.
In order to obtain a fundamental understanding of the influence of the
defects introduced upon fast neutron irradiation on the electronic behaviour
of SiC, radiation damage studies have also been made on p- and η-type single
crystals of SiC by means of resistivity and Hall effect measurements. Upon
neutron bombardment p-type SiC is converted to η-type material. This indi­
cates that the predominant defect is an effective donor state which is located
at about 0.24 eV below the conduction band. The η-doped material remains of
the same type after various periods of exposure.
The relaxation processes of defects during heat treatment have been exami­
ned by the isochronal pulse annealing technique. No measurable annealing
occurs below 400 °C. Photospectrometric measurements on the other hand
reveal an annealing process starting at 300 °C.
relatively low limiting value of electron concentration. This would correspond
to a shift of the Fermi-level of the intrinsic region to a position in the lower
part of the upper half of the forbidden energy gap. Not much annealing is found
on measuring the change of the electrical characteristics upon pulse annealing.
Because of the smallness of the width of the space-charge layer (about 1
micron), the grown SiC diodes could not be used as detectors.
In order to obtain a fundamental understanding of the influence of the
defects introduced upon fast neutron irradiation on the electronic behaviour
of SiC, radiation damage studies have also been made on p- and η-type single
crystals of SiC by means of resistivity and Hall effect measurements. Upon
neutron bombardment p-type SiC is converted to η-type material. This indi­
cates that the predominant defect is an effective donor state which is located
at about 0.24 eV below the conduction band. The η-doped material remains of
the same type after various periods of exposure.
The relaxation processes of defects during heat treatment have been exami­
ned by the isochronal pulse annealing technique. No measurable annealing
occurs below 400 °C. Photospectrometric measurements on the other hand
reveal an annealing process starting at 300 °C. EUR 431.e
EUROPEAN ATOMIC ENERGY COMMUNITY - EURATOM
SOLID STATE NEUTRON DETECTOR
by
S. AMELINCKX (C.E.N.), R. DE CONINCK (C.E.N.),
M. DENAYER (C.E.N.), A. GIJS (C.E.N.),
M. HEERSCHAP (EURATOM), P. NAGELS (C.E.N.),
and L. VAN GOOL (C.E.N.)
1964
EURATOM/UNITED STATES AGREEMENT FOR COOPERATION
EURAEC Report No 587 established by the
Centre d'Etude de l'Energie Nucléaire C.E.N., Mol (Belgium)
Euratom Contract No 079-61-10 RDB Supervisor S. Ame I inckx (S .CK» )
M. Heerschap (Euratom! Research Associates
P. Nage Is (S„C.K.)
R. De Coninck !S„C„K,, )
M, Denayer (S.C.K. )
A. Gijs (SoCoK.ì Technical Assistance
Lo Van Gooi (S„CK„ )
Imputation budgétaire 6t 2121
Ro2292
c/349/63 3 -TABLE OF CONTENTS
Pages
¡NTRODUCTION
2„ RADIATION DAMAGE AND ANNEALING STUDIES OF GROWN SiC p~n JUNCTIONS 9
2*1. Irradiation facility 9
2o2, Voltage­currentcharacteristics measuring circuit Î0
2u3u The changeoftheelectrical characteristicsandofthe photo­­!0
currentofgrownSICp­ηjunctions upon reactor'irradiation
at 80'C
2o4o AnnealingofIrradiatedSiC ρ n junctions ­ \2
2»5o Reactor irradiation of grown SiC diodesatatemperature of !2
500^0
2„6U Photospectrometric measurements ¡3
3U RADIATION DAMAGE INSINGLECRYSTALSOFSILICON CARBIDE !3
3UI o I ntroduct ion ;3
3o2„VANDERPAUW'smethod¡4
3.3»Experimental>4
3<.4„ Resistivity and Ha M constant measurements of SiC singles5
crysta Is
3„5. Neutron irradiation of SiC single crystals ¡Q
3o6o Puise annealing in p­ and η­typeSiCafterneutron exposure¡9
REFERENCES pi
0/349/63 ­ 4 ­LIST OF FIGURES
Schematic view of the oven in the BRI reactor. Fig. I . ­
Voltage­current characteristics measuring circuit. Fig. 2. ­
Schematic representation of the change of the forward and reverse cha­Fig. 3. ­
racteristics of a SiC p­η junction upon reactor irradiation,,
Change of the reverse current at a bias voltage of 0.9 volt and of the Fig. 4. ­
"foot" at a bias voltage of 0.8 volt.
Change of the forward current of junction Ph­h at a bias voltage of !„7 Fig. 5. ­
volt and of a junction Ph at a bias voltage of 2 volts.
Change of the short­circuit photocurrent upon reactor irradiation of a Fig. 6. ­
sample junction of series H­75 and P­15.
Fig. 7. ­ Ini versus voltage curves of the forward characteristics of junction
Ph­h at various doses of reactor irradiation, obtained by subtracting
the "foot" from the original characteristics.
Fig. 8. ­ Change of forward characteristic upon pulse annealing.
Change of reverse c upon pulse » Fig. 9. ­
Fig. 10. ­ Change of the forward and the reverse current at a constant b!as voltage
of a grown SiC diode during reactor irradiation at a temperature of 500°C:
Fig. II. ­ Surface conduction after heat treatment at l000oC.
Fig. 12. ­ Change of photocurrent of a grown SiC diode at 500"C during reacto?· ■ra~
d iat i on.
Fig. 13. ­ Change of transmission of a SiC single crystal upon reactor irradiation
and subsequent annealing.
Arrangement of probes for resistivity and Hal! measurements. Fig. 14.
fR I Fig. 15. The function f used for