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Proceedings Paper • Open Access

Development and characterisation of MCT detectors for space astrophysics at CEA
Author(s): O. Boulade; N. Baier; P. Castelein; C. Cervera; P. Chorier; G. Destefanis; B. Fièque; O. Gravrand; F. Guellec; V. Moreau; P. Mulet; F. Pinsard; J.-P. Zanatta

Paper Abstract

The Laboratoire Electronique et Traitement de l’Information (LETI) of the Commissariat à l’Energie Atomique (CEA, Grenoble, France) has been involved in the development of infrared detectors based on HgCdTe (MCT) material for over 30 years, mainly for defence and security programs [1]. Once the building blocks are developed at LETI (MCT material process, diode technology, hybridization, …), the industrialization is performed at SOFRADIR (also in Grenoble, France) which also has its own R&D program [2].
In past years, LETI also developed infrared detectors for space astrophysics in the mid infrared range – the long wave detector of the ISOCAM camera onboard ISO – as well as in the far infrared range – the bolometer arrays of the Herschel/PACS photometer unit –, both instruments which were under the responsibility of the Astrophysics department of CEA (IRFU/SAp, Saclay, France).

Nowadays, the infrared detectors used in space and ground based astronomical instruments all come from vendors in the US. For programmatic reasons – increase the number of available vendors, decrease the cost, mitigate possible export regulations, …– as well as political ones – spend european money in Europe –, the European Space Agency (ESA) defined two roadmaps (one in the NIR-SWIR range, one in the MWIR-LWIR range) that will eventually allow for the procurement of infrared detectors for space astrophysics within Europe.
The French Space Agency (CNES) also started the same sort of roadmaps, as part of its contribution to the different space missions which involve delivery of instruments by French laboratories. It is important to note that some of the developments foreseen in these roadmaps also apply to Earth Observations.
One of the main goal of the ESA and CNES roadmaps is to reduce the level of dark current in MCT devices at all wavelengths. The objective is to use the detectors at the highest temperature where the noise induced by the dark current stays compatible with the photon noise, as the detector operating temperature has a very strong impact at system level. A consequence of reaching low levels of dark current is the need for very low noise readout circuits.

CEA and SOFRADIR are involved in a number of activities that have already started in this framework. CEA/LETI does the development of the photo-voltaic (PV) layers – MCT material growth, diode technologies–, as well as some electro-optical characterisation at wafer, diode and hybrid component levels, and CEA/IRFU/SAp does all the electro-optical characterisation involving very low flux measurements (mostly dark current measurements). Depending of the program, SOFRADIR can also participate in the development of the hybrid components, for instance the very low noise readout circuits (ROIC) can be developed either at SOFRADIR or at CEA/LETI.
Depending of the component specifications, the MCT epitaxy can be either liquid phase (LPE, which is the standard at SOFRADIR for production purposes) or molecular beam (MBE), the diode technology can be n/p (standard at LETI and SOFRADIR) or p/n (under development for several years now) [3], and the input stage of the ROIC can be Source Follower per Detector (SFD for very low flux low noise programs) or Capacitive Trans Impedance Amplifier (CTIA for intermediate flux programs) [4].

This paper will present the different developments and results obtained so far in the two NIR-SWIR and MWIR-LWIR spectral ranges, as well as the perspectives for the near future. CEA/LETI is also involved in the development of MCT Avalanche Photo Diodes (APD) that will be discussed in other papers [5,6].

Paper Details

Date Published: 17 November 2017
PDF: 9 pages
Proc. SPIE 10563, International Conference on Space Optics — ICSO 2014, 105631W (17 November 2017); doi: 10.1117/12.2304252
Show Author Affiliations
O. Boulade, Service d’Astrophysique, Institut de Recherche sur les lois Fondamentales de l’Univers, CEA Saclay (France)
N. Baier, Laboratoire Electronique et Traitement de l’Information, CEA Grenoble (France)
P. Castelein, Laboratoire Electronique et Traitement de l’Information, CEA Grenoble (France)
C. Cervera, Laboratoire Electronique et Traitement de l’Information, CEA Grenoble (France)
P. Chorier, SOFRADIR (France)
G. Destefanis, Laboratoire Electronique et Traitement de l’Information, CEA Grenoble (France)
B. Fièque, SOFRADIR (France)
O. Gravrand, Laboratoire Electronique et Traitement de l’Information, CEA Grenoble (France)
F. Guellec, Laboratoire Electronique et Traitement de l’Information, CEA Grenoble (France)
V. Moreau, Service d’Astrophysique, Institut de Recherche sur les lois Fondamentales de l’Univers, CEA Saclay (France)
P. Mulet, Service d’Astrophysique, Institut de Recherche sur les lois Fondamentales de l’Univers, CEA Saclay (France)
F. Pinsard, Service d’Astrophysique, Institut de Recherche sur les lois Fondamentales de l’Univers, CEA Saclay (France)
J.-P. Zanatta, Laboratoire Electronique et Traitement de l’Information, CEA Grenoble (France)


Published in SPIE Proceedings Vol. 10563:
International Conference on Space Optics — ICSO 2014
Zoran Sodnik; Bruno Cugny; Nikos Karafolas, Editor(s)

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