Megapixel Longwave Infrared SLS FPAs for High Spatial Resolution Earth Observing Missions

Earth observing missions like NASA's LANDSAT Data Continuity Mission - Thermal Infrared Sensor (LDCM-TIRS) require greater spatial resolution of the earth than the ~ 100m provided by the current instrument. Improving resolution to the desired ~ 30m requires increasing the number of pixels on target from the current 640x3 to ~ 2048x3. The TIRS instrument contains 640x512 longwave infrared quantum well infrared photodetector focal plane arrays (LWIR QWIP FPAs) jointly developed by NASA/GSFC and QmagiQ. We propose to achieve the higher pixel resolution while simultaneously improving quantum efficiency and operating temperature by using antimony-based strained layer superlattice (SLS) detectors. A key challenge is dealing with the effects of reducing pixel pitch from 25 microns down to ~ 10 microns, viz. optical fill-factor, optical crosstalk, processing difficulties, pixel operability, etc. As a stepping stone in Phase I, we propose to develop and deliver SLS FPAs with 1280x1024 format on 12 micron pitch that will address these challenges and quantify the effectiveness of our solutions. In Phase II, we will increase FPA format to 2048x2048 and push cutoff wavelength to the longest possible value while still hitting desired quantum efficiency and operating temperature targets in consultation with NASA/GSFC. Several FPAs will be delivered to NASA for evaluation. More »