Space astronomy requires large-area cryogenic infrared focal plane arrays ͑FPAs͒ with high quantum efficiency, extremely low dark current, low power dissipation, and background limited noise performance. To meet these requirements, especially at temperatures of 5-15 K, Santa Barbara Research Center designed and fabricated a new multiplexer, CRC-744. The FPAs made by bonding InSb detector arrays to CRC-744 multiplexers were evaluated at the University of Rochester. The best array achieved the read noise of 5 e Ϫ with 12 s integration and 7 e Ϫ with 200 s integration with Fowler-64 sampling at 15 K, the average dark current of Ͻ0.2 e Ϫ /s at both 15 and 29 K, and the average quantum efficiency of 87% at both 15 and 29 K. The 10%-90% rise time was 4 s driving a 600 pF external load. The power dissipation was 0.3-0.4 mW when running flat-out ͑100% duty cycle͒. The full well capacity was 10 5 e Ϫ ͑230 mV͒ with 400 mV of applied bias. The above test results demonstrate that the FPAs meet background-limited space experiment requirements. The CRC-744 multiplexer works well down to at least 5 K ͑the lowest temperature of our tests͒.
1K × 1K Si:As Impurity Band Conduction (IBC) arrays have been developed by RVS for the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI). MIRI provides imaging, coronagraphy, and low and medium resolution spectroscopy over the 5 -28 µm band. The IBC devices are also suitable for other low-background applications. The Si:As IBC detectors have a pixel dimension of 25 µm and respond to infrared radiation between 5 and 28 µm, covering an important Mid-IR region beyond the 1 -5 µm range covered by the JWST NIRCam and NIRSpec instruments. Due to high terrestrial backgrounds at the longer Mid-IR wavelengths, it is very difficult to conduct ground-based observations at these wavelengths. Hence, the MIRI instrument on JWST can provide science not obtainable from the ground. We describe results of the development of a new 1024 × 1024 Si:As IBC array that responds with high quantum efficiency over the wavelength range 5 to 28 µm. The previous generation's largest, most sensitive infrared (IR) detectors at these wavelengths were the 256 × 256 / 30 µm pitch Si:As IBC devices built by Raytheon for the SIRTF/IRAC instrument 1 . Detector performance results will be discussed, including relative spectral response, Responsive Quantum Efficiency (RQE) vs. detector bias, and dark current versus temperature. In addition, Sensor Chip Assembly (SCA) data will be presented from the first Engineering SCAs. The detector ROIC utilizes a PMOS Source Follower per Detector (SFD) input circuit with a well capacity of about 2 × 10 5 electrons. The read noise of the "bare" MUX is less than 12 e-rms with Fowler-8 sampling at an operating temperature of 7 K. A companion paper by Craig McMurtry (University of Rochester) will discuss the details of SB305 MUX noise measurements 2 . Other features of the IBC array include 4 video outputs and a separate reference output with a frame rate of 0.36 Hz (2.75 sec frame time). Power dissipation is about 0.5 mW at a 0.36 Hz frame rate. Reset modes include both global reset and reset by row (ripple mode). Reference pixels are built-in to the output data stream. The 1K × 1K IBC is packaged in a robust modular package that consists of a multilayer motherboard, SiC pedestal, and cable assembly with 51-pin MDM connector. All materials of construction were chosen to match the thermal expansion coefficient of Silicon to provide excellent module thermal cycle reliability for cycling between room temperature and 7 K.
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