Development of a next-generation thermopile detector for cold-body space applications

Due to the low temperature of space bodies, such as the outer planets of the solar system and certain regions of the moon, many thermophysical processes reveal themselves in the infrared and far-infrared. Thus, the capability to measure and analyze the infrared spectrum in space is critical. Thermopile detectors are a class of thermal detectors that can convert incoming infrared radiation into accurate temperature maps of various surfaces without the need of cooling. However, a larger detector array is needed to allow for large maps of extremely cold (< 100 K) celestial bodies. In this work, therefore, we model, develop, and test a next-generation thermopile detector with a 4x larger format size than the state-of-the-art with diffraction-limited pixels. We report the highest specific detectivity of 1x10 9 cmHz 1/2 /W for a thermopile detector with a format size of 64x32 pixels. In addition, we develop a process to hybridize these detectors with readout integrated circuits (ROICs) using indium bump bonding. A prototype focal plane module is fabricated to accommodate the hybridized detector/ROIC and fit in a compact instrument initially devised for moon rovers.