Starting date : Jan 2018 > Nov 2021
Lifetime: 42 months
Program in support : H2020 Space–compet 17
Status of project : in progress
CEA-Leti's contact :
> Pierre Castelein
> Laurent Fulbert > Roch Espiau de Lamaestre
Project Coordinator: Thales Alenia Space (FR)
Partners: - FR: III-V Lab, CEA-Leti, Thales Alenia Space
- NO: Norsk Elektro Optikk AS
- UK: Rutherford Appleton Laboratory, University of Sheffield
Investment: € 2.8 mi
EC Contribution: € 2.8 mi
| Stakes
- In SWIR-UP, CEA-Leti is upgrading p/n HgCdTe photodiode technology, which has already beenmatured for low operating temperatures at SOFRADIR, an industrial partner in infrared imagery forover 25 years. Revision of the design of the epilayers and p/n photodiode has enabled CEA-Leti toachieve a new state of the art at higher operating temperatures. This work serves as a referencefor the new extended InGaAs technology also developed in the project. Adjusted epilayers havebeen grown and will be processed to fabricate 2D photodiode arrays (TV format, 15 μm pitch). Thecut-off wavelength is around 2.45 μm.
- Hybridize the 2D HgCdTe and extended InGaAs detector arrays on existing read-out integrated circuits supplied by SOFRADIR
- Participate in packaging of the resulting focal plane arrays onto fan-out ceramics to be installed in a specifically designed cryostat
- Permit initial comparison of the electro-optical performance characteristics of HgCdTe and extended InGaAs photodiode technologies in terms of dark current, noise, quantum efficiency, response and operability. Particular emphasis will be placed on the level of dark current with respect to the operating temperature since as this important value is key to avoiding cryogenic cooling.
- Space missions performing high-resolution Earth observation (including greenhouse gas monitoring) require optical sensors covering both visible channels and the Short Wavelength Infra-Red (SWIR) band. With regard to SWIR optical sensors, the current approach in Europe has been implementation of HgCdTe N/P sensors cooled to cryogenic temperature. SWIR-UP is an H2020 project, whose goal is to develop an alternative photosensitive material to those used in today’s HgCdTe N/P sensors. It is focusing on «III-V»: a material comprising an InGaAs/GaAsSb super-lattice matched to an InP substrate.
The primary objective of the project is to extend the cut-off wavelength (currently limited to 1.7 μm for off-the-shelf detectors operating at room temperature) to 2.5 μm by adding additional SWIR bands to the visible channels commonly used by instruments dedicated to Earth observation from space. SWIR-UP sensor technologies also offer alternatives to HgCdTe N/P detectors for commercial applications in the SWIR spectral range. These include hyperspectral imaging systems (for airborne, field, laboratory and industrial applications) and Lidar (for active imaging applications).
A secondary objective is to achieve higher operating temperatures for focal plane arrays: allowing operation as close as possible to room temperature (230-290 K) compared with typically 200-210 K for today’s HgCdTe detectors. This eliminates cryogenic cooling to improve the miniaturization, power reduction, efficiency and versatility of optical payloads, all of which could offer opportunities for greater functionality.
With in the scope of this action, new SWIR-UP technology is also being compared to current reference II-VI technology embodied by HgCdTe P/N material. This should lead to a technological prioritization based on application type since each material has specific advantages. “II-VI” material, already optimized for cooled astronomical application, is being upgraded for operation at higher temperatures.
The SWIR-UP project also involves manufacturing and testing 2D arrays (640 x 512, 15 μm pitch, cut-off wavelength approximately 2.5 μm) with a sensing module based on both III-V and II-VI technologies. Reaching TRL5 at the end of the project, the best performing technology will enter the industrialization phase and be commercially integrated around 2022.
IMPACT
- The SWIR-UP project is directly expanding the Earth observation technology portfolio to ensure Europe’s leadership in SWIR imaging at very low power consumption. The project will impact many other markets: military, civilian and professional (hyperspectral imaging, scientific imaging, machine vision, etc.).
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