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Martineau L.,SOFRADIR | Berthoz J.,SOFRADIR | Rubaldo L.,SOFRADIR
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

Spatial applications are challenging infrared (IR) technologies requiring the best system performances. Usually, the need is a trade-off between the spatial response and signal to noise ratio (SNR) of the IR detector, and in particular the dark current performance. Measuring dark current performances for IR detectors at low temperature require an understanding of detector physics, readout circuit design and also test equipment limitation. This paper describes possible issues associated with dark current measurements on n-on-p Mercury Cadmium Telluride (MCT) pixel design. © 2016 SPIE.


Martineau L.,SOFRADIR | Rubaldo L.,SOFRADIR | Chabuel F.,SOFRADIR | Gravrand O.,CEA Grenoble
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

Spatial applications are challenging infrared (IR) technologies requiring the best system performances. Usually, the need is a trade-off between the signal to noise ratio (SNR) and spatial response of the IR detector, and in particular the modulation transfer function (MTF) performance. MTF optimization requires a deep understanding of detector physics and the use of evaluation tools. This paper describes the optimization of an n-on-p Mercury Cadmium Telluride (MCT) pixel design using a MTF mathematical model to predict the performance. © 2013 SPIE.


Gravrand O.,CEA Grenoble | Baier N.,CEA Grenoble | Ferron A.,CEA Grenoble | Rochette F.,CEA Grenoble | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

The actual trend in quantum IR detector development is the design of very small pixel pitch large arrays. From previously 30μm pitch, the standard pixel pitch is today 15μm and is expected to decrease to 12μm in the next few years. Furthermore, focal plane arrays (FPA) with pixel pitch as small as small as 10μm has been demonstrated. Such ultra-small pixel pitches are very small compared to the typical length ruling the electrical characteristics of the absorbing materials, namely the minority carrier diffusion length. As an example for low doped N type HgCdTe or InSb material, this diffusion length is of the order of 30 to 50μm, i.e. 3 to 5 times the targeted pixel pitches. This has strong consequences on the modulation transfer function (MTF) for planar structures, where the lateral extension of the photodiode is limited by diffusion. For such aspect ratios, the self-confinement of neighboring diodes may not be efficient enough to maintain optimal MTF. Therefore, this issue has to be addressed in order to take full benefits of the pixel pitch reduction in terms of image resolution. This paper aims at investigating the MTF evolution of HgCdTe and InSb FPAs decreasing the pixel pitch below 15μm. Both experimental measurements and finite element simulations are used to discuss this issue. Different scenarii will be compared, namely deep mesa etch between pixels, internal drift, surface recombination, thin absorbing layers. © 2014 SPIE.


Gravrand O.,CEA Grenoble | Mollard L.,CEA Grenoble | Boulade O.,CEA Saclay Nuclear Research Center | Moreau V.,CEA Saclay Nuclear Research Center | And 2 more authors.
Journal of Electronic Materials | Year: 2012

We report the first results of work carried out at CEA and Sofradir to build ultralow-dark-current focal-plane arrays (FPAs) in the short-wave infrared range (SWIR) for space applications. These FPAs are designed to detect very low flux in the 2-μm wavelength range. To this end, Sofradir has designed a source follower per detector read-out circuit (ROIC, 384 × 288, 15 μm pitch). This ROIC has been hybridized on different HgCdTe diode configurations processed at CEA-LETI, and low-flux characterizations have been carried out at CEA-IRFU at low temperature (from 60 K to 160 K). Both ion-implanted p/n and n/p diodes have been evaluated. The metallurgical nature of the absorbing layer has also been examined, and both molecular-beam epitaxy (MBE) and liquid-phase epitaxy (LPE) have been applied. Dark-current measurements are discussed in comparison with previous results from the literature. State-of-the-art dark currents are recorded for temperatures higher than 120 K. At temperatures lower than 100 K, the decrease in dark current flattens out for both technologies. In this region, currents between 0.4 e -/s/pixel and 0.06 e -/s/pixel are reported. © 2012 TMS.


Berthoz J.,SOFRADIR | Rubaldo L.,SOFRADIR | Grille I.R.,SOFRADIR | Gravrand O.,CEA Grenoble
2014 11th International Workshop on Low Temperature Electronics, WOLTE 2014 | Year: 2014

Reduction of pixel pitch in infrared detector improves the spatial resolution and the range. The key performance of the detector range is the modulation transfer function (MTF). In an ideal case MTF can be express as the Fourier transformation of its square response. For small pixel, electrical lateral diffusion tends to reduce MTF from its ideal value. Computation shows that at 10μm the MTF is better than at 15μm for a given frequency. However, because of electric lateral diffusion, MTF at 10μm is more distant from its ideal value. Computations show that mesa can be used to have a better MTF. © 2014 IEEE.


Manissadjian A.,SOFRADIR | Rubaldo L.,SOFRADIR | Rebeil Y.,SOFRADIR | Kerlain A.,SOFRADIR | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

Cooled IR technologies are challenged for answering new system needs like the compactness and the reduction of cryopower which is a key feature for the SWaP (Size, Weight and Power) requirements. Over the last years, SOFRADIR has improved its HgCdTe technology, with effect on dark current reduction, opening the way for High Operating Temperature (HOT) systems that can get rid of the 80K temperature constraint, and therefore releases the Stirling cooler engine power consumption. Performances of the 640×512 15μm pitch LW detector working above 100K will be presented. A compact 640×512 15μm pitch MW detector presenting high EO performance above 130K with cut-off wavelength above 5.0μm has been developed. Its different performances with respect to the market requirements for SWaP will be discussed. High performance compact systems will make no compromise on detector resolution. The pixel pitch reduction is the answer for resolution enhancement with size reduction. We will therefore also discuss the ongoing developments and market needs for SWaP systems. © 2012 SPIE.


Vuillermet M.,SOFRADIR
Defence Science Journal | Year: 2013

This short article describes the recent developments of cooled infrared products at Sofradir. These developments are driven by the future systems needs like the increase in resolution and detection range, the reduction of the detector size and consequently of the pixel pitch and the reduction of the power consumption. To answer to these needs, Sofradir develops in collaboration with the French infrared laboratory (CEA-LETI) new products based on Mercury Cadmium Telluride technology: Scorpio LW 640 × 512/15 μm pitch, sensitive in the long wavelength, Jupiter MW 1280 × 1024/15 μm pitch sensitive in mid wavelength, HOT detectors operating at 150 K and the 10 μm pitch detectors. © 2013, DESIDOC.


Chorier P.,SOFRADIR | Delannoy A.,SOFRADIR
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

Sofradir is one of the leading companies that develop and produce infrared detectors. Space applications have become a significant activity and Sofradir relies now on 20 years of experience in development and production of MCT infrared detectors of 2nd and 3rd generation for space applications. Thanks to its capabilities and experience, Sofradir is now able to offer high reliability infrared detectors for space applications. These detectors cover various kinds of applications like hyperspectral observation, earth observations for meteorological or scientific purpose and science experiments. In this paper, we present a review of latest Sofradir's development for infrared space applications. A presentation of Sofradir infrared detectors answering hyperspectral needs from visible up to VLWIR waveband will be made. In addition a particular emphasis will be placed on the different programs currently running, with a presentation of the associated results as they relate to performances and qualifications for space use. © 2011 SPIE.


Breniere X.,SOFRADIR | Rubaldo L.,SOFRADIR | Dupont F.,SOFRADIR
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

Sofradir IR detectors are being deployed in a lengthening line of space applications (earth observation, atmospheric observation, scientific missions, etc...), and also in the whole range of tactical applications (portable cameras, missile seekers, land, airborne and naval systems, etc...). Sofradir is taking advantage of these two areas. Firstly, space applications are developing new advances and technologies that can later be introduced in the production of IR detectors for tactical applications, thereby increasing their quality and reliability. In addition, Sofradir can better satisfy space application requirements for failure rates, as these can only be demonstrated with the large number of detectors manufactured, which tactical applications provide. As a result, this approach offers a continuous cycle for reliability of IR detectors, accelerating reliability growth in production, and at the same time meeting requirements for space applications. This paper presents recent improvements introduced in production lines of HgCdTe detectors, that increase performances, image quality, and reliability. © 2014 SPIE.


Vuillermet M.,SOFRADIR | Tribolet P.,SOFRADIR
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

Cooled IR technologies are challenged for answering new system needs like the reduction of energy. This reduction is requested in new IR system design in particular for cooled IR detection. The goal is to reduce system sizes, to increase system autonomies and reliabilities and globally to reduce system costs! One of the key drivers for cooled systems is the cooler and the operating temperature. As far as operating temperature is concerned, Sofradir put a lot of efforts for years for adapting its technologies to increase the operating temperatures of IR detectors. Main examples are dealing with long wave staring arrays based on QWIP technology and on MCT technology as well as medium wave staring arrays using MCT technologies. © 2010 Copyright SPIE - The International Society for Optical Engineering.

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