Recent Trends in the Development of CdTe and CdZnTe Semiconductor Detectors for Astrophysical Applications S. Del Sordo 1 , L. Abbene 1,2 , N. Auricchio 1 ,E. Caroli 1 , M. Quadrini 1 , J.B. Stephen 1 , A. Zappettini 3 , R.M. Curado Da Silva 4 , O. Limousin 5 , A. Meuris 5 and P. Ubertini 1 1 IASF-INAF, Italy 2 DiFTeR Università di Palermo, Palermo, Italy 3 IMEM-CNR, Parma, Italy 4 Departmento de Física, Universidade de Coimbra, Coimbra, Portugal The Extreme Sky " Sampling the Universe above 10 keV" 13 - 17 October 2009 Otranto
Transcript
Recent Trends in the Development of CdTe and CdZnTe Semiconductor Detectors for
Astrophysical Applications
S. Del Sordo1, L. Abbene1,2, N. Auricchio 1 ,E. Caroli1, M. Quadrini1, J.B. Stephen1 , A. Zappettini3, R.M. Curado Da Silva4,
O. Limousin5, A. Meuris5 and P. Ubertini1
1IASF-INAF, Italy2DiFTeR Università di Palermo, Palermo, Italy
3IMEM-CNR, Parma, Italy4Departmento de Física, Universidade de Coimbra, Coimbra, Portugal
5CEA – DSM - Irfu - Service d’Astrophysique, Saclay, France
The Extreme Sky
" Sampling the Universe above 10 keV"
13 - 17 October 2009 Otranto
The Extreme Sky, Otranto16th October 2009
Outline
Scenario (projects and collaborations)
CdTe / CdZnTe X-ray and gamma ray detectors
Detector prototypes
Work in progress and future developments
Conclusions
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Projects and Collaborations
Progetto ASI Alte Energie (Study for the Gamma Ray Imager mission)
Progetto PRIN INAF SGRIP (funded by INAF)Development of an high efficiency wide band 3D CZT detector prototype for Laue telescope focal plane
Progetto PRIN (funded by MIUR)Growth technologies and spectroscopic optimization for X and Gamma ray detectors based on CdTe/CdZnTe.
IASF-INAF (Milano Bologna Roma Palermo) IMEM-CNR di Parma (crystal growth) Università di Lecce (crystal growth and bonding) IMM-CNR di Lecce (bonding and electrical characterization) DIFTER Università di Palermo (medical applications)
The Italian collaboration
• ESRF Grenoble
• Leicester University
• DTU Space Copenaghen
• Coimbra University
• CEA Saclay Paris
• ICE-CSIC Barcelona
International collaborations
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CdTe and CdZnTe I
High Z semiconductors
(Zmax = 52)
Wide band gap semiconductors
Del Sordo S. et al., Sensors, Vol. 9, 3491-3526, 2009.
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CdTe and CdZnTe II
Critical Issues
Poor transport properties of the charge carriers:
hh ~ 10-5-10-6 cm2/ V
ee ~ 10-2-10-3 cm2/V)
Small electrical signals at the electrodes
Small crystal size: typically < 2 cm3
Development of single charge carrier sensing detectors (pixel, strip, Frisch grid, multiple electrodes) to overcome the poor transport properties of the holes is mandatory.
L. Abbene et al., NIM A 583 (2007) 324-331.
1 mm 1 mm
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CdTe and CdZnTe III
Suppliers of Spectrometer grade crystals
Italian group at IMEM-CNR (A. Zappettini): CdZnTe crystals grown by the boron oxide encapsulated vertical Bridgman technique
A. Zappettini et al., IEEE Nucl. Sci. Symp. Conf. Rec. 2008, 118-121.
2-inch CdZnTe crystal
1.1 mm
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CdZnTe detector prototypes
DETECTORS CHARACTERISTICS
Pixel detectors CZT (eV Products)
Geometric surface 10×10 mm2
Active area 8×8 mm2
Thickness 1 mm and 2 mm
Number of pixels 256
Pitch 0.5 mm
(0.45 mm anodes, 0.05 mm gap)
focal plane detector prototypes for Hard X-ray multilayer telescopes (10-
100 keV)
CZT pixel detectors
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Energy (keV)
Energy resolution (%)
Peak to valley ratio (2 x FWHM)
59.5 5.80 ± 0.16 28.1 ± 1.1
88,1 3.9 ± 0.2 19.5 ± 1.1
CZT pixel detectors performance
L. Abbene et al., JAP, Vol. 105, 2009.
CdZnTe detector prototypes
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thickness 1 mm 2 mm
energy resolution (%) (59.5 keV)
5.80 ± 0.16 5.50 ± 0.10
energy resolution (%) (88.1 keV)
3.9 ± 0.2 3.50 ± 0.13
deviation of the FW.1M/FWHM ratio from the Gaussian
ratio (1.82) (59.5 keV)
8 % 5 %
deviation of the FW.1M/FWHM ratio from the Gaussian
ratio (1.82) (88.1 keV)
16 % 10 %
“Small pixel effect”
H. Barrett, J. Eskin, H. Barber, Phys. Rev. Lett. 75 (1995) 156
CdZnTe detector prototypes
CZT pixel detectors performance
2 mm thick detector vs 1 mm
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CdZnTe detector prototypes
CZT pixel detector for the POLCA II Experiment (POLarimetry with CdZnTe Arrays)
Detector CZT Imarad4x4 cm2, 5 mm thickHV = -600 V16x16 pix with 2.5 mm pitch11x11 + 7 pix used
Readout Electronics
8 eV products ASIC 16 channels/chip33/50/100/200 sel. Gain0.6/1.2/2.4/4 μs shaping time
The POLCA quick look S/W user interface (LABVIEW)
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CdZnTe detector prototypes
Polca experiment: Set-up at ESRF beam line ID15B and Results
P o la r ised B ea m E n erg y ra n g e: 1 0 0 k e V to ~ 1 M e V
Anode side: 8 anodes strips 0.15 mm wide (pitch=2.5 mm)
correcting field strips 0.15 mm wide gap between strips=0.15 mm
Cathode side: 4 cathodes strips 2.4 mm wide gap between strips=0.10 mm
3D detector prototype packaging scheme: The detector assembly is built with 8 identical modules packed together (64 anodes and 32
cathodes).
I/O pads Alumina support
Front end electronics board
data handling and logic board
Small 3D CZT position sensitive spectrometer (SmallGRIPrototype)
Redout Electronics NOVARAD Rena3
CdZnTe detector prototypes
See Poster E. Caroli et al. SGRIP …
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Future Developments The POLCaliste experiment
Low noise readout electronics r.m.s. 80 e-
Caliste Module
CdTe Schottky detector
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Future Developments The POLCaliste experiment
Polarimetric measurements at ESRF with the PolCaliste prototype are foreseen in 2010. We foresee to use in a first run the 64 ch device and in a next step the new 256 ch device. The device thickness will be 0.5, 1, 2 mm
Energy resolution 1.5 % (FWHM) @ 59.5 keV
T = -15 °C
POLCaliste Experiment (POLarimetry with Caliste)
Caliste module performance
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Conclusions (I)
Italian CZT detector development (crystal growth and detectors assembly) activities are in progress with quite good expectations.
Experimental activities devoted to characterize imaging spectrometer operative in the 10 -100 keV energy band are in progress.
The SGRIP experiment (considered as a pathfinder for GRI) is in an advanced realization phase. The study of the prototype performances, foreseen in the 2010, will allow the optimization of the main operative parameters for a detector operative up to 800 keV in stack configuration.
The polarimetric performances of the POLCAII experiment are under evaluation. Measurements with the improved POLCaliste experiment are foreseen in the 2010 at ESRF.
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Very recently ASI funded a technological project named : “LAUE - A Gamma Ray Lens”. In this project our collaboration has the responsibility of the focal plane detector (4 x 4 cm2 , 0.5 mm spatial resolution, good energy resolution) for the test of the lens prototypes. In this framework one of the most appealing possibilities will be the use of an array of Calliste detectors in the new 256 channel version.
