Development and testing of a 1024×1024 pixel Si:As IBC detector for SOFIA-like applications

Airborne and space telescope astronomical observations in the 5-25 micron wavelength region are critical for understanding the physical conditions, composition, chemistry, and excitation of many environments in the interstellar medium, external galaxies, solar system objects, extra-solar systems, and stars. The scientific impact is particularly unique in the 5-8 micron and 14-25 micron regions which are inaccessible or poorly observed from ground-based observatories. Large format mid-infrared detectors sensitive over these wavelengths and operable under moderate backgrounds (~10⁶ photons/s/pixel at R=2000, at 10 microns) are essential for efficient large-area survey imaging and for taking moderate resolution spectra over a large spectral range. Both SOFIA and passively cooled Explorer observatories could benefit from this technology. Current first-light SOFIA instruments use small-format mid-infrared focal plane arrays of sizes 256 × 256 pixels. With the collaboration of Raytheon Infrared Operations, NASA-Ames Research Center has developed and tested the first 1024 × 1024 mid-infrared device suitable for operating under moderate backgrounds: a combination of the ALADDIN III readout multiplexer, cryo-processed for 6 K operation, with Si:As IBC detector material designed for high QE. This device has exhibited low dark current, moderate noise levels, and > 200,000 electron linear well size at 6 K operation. We conclude with suggestions for future device development for optimal performance under moderate background, SOFIA- and low Earth orbit observing conditions.