T2SLS Digital Focal Plane Arrays for Earth Remote Sensing Instruments
Presenting Author: Sarath Gunapala
Organization: Jet Propulsion Laboratory
Co-Author(s): David Ting, Alexander Soibel, Arezou Khoshakhlagh, Sir Rafol, Cory Hill, Anita Fisher, Brian Pepper, Kwong-Kit Choi, Arvind D'Souza, and Christopher Masterjohn
Long-wavelength infrared (LWIR) focal plane arrays (FPAs) needed for Earth Science imaging, spectral imaging, and sounding applications have always been among the most challenging in infrared photodetector technology due to the rigorous material growth, device design and fabrication demands. Future small satellite missions will present even more challenges for LWIR FPAs, as operating temperature must be increased so that cooler (and radiator) volume, mass, and power can be reduced. To address this critical need, we are working on following three technologies. 1) Type-II superlattice (T2SL) barrier infrared detector (BIRD), which combines the high operability, spatial uniformity, temporal stability, scalability, producibility, and affordability advantages of the quantum well infrared photodetector (QWIP) FPA with the better quantum efficiency and dark current characteristics. A long-wavelength infrared (LWIR) T2SLS BIRD FPA is a key demonstration technology in the (6U) CubeSat Hyperspectral Thermal Imager (HyTI) funded under the ESTO InVEST Program. 2) The resonator pixel technology, which uses nano-photonics light trapping techniques to achieve strong absorption in a small detector absorber volume, thereby enabling enhanced QE and/or reduced dark current. 3) High dynamic range 3D Readout IC (3D-ROIC), which integrates a digital reset counter with a conventional analog ROIC to provide a much higher effective well capacity than previously achievable. The resulting longer integration times are especially beneficial for high flux/dark current LWIR applications as they can improve signal-to-noise ratio and/or increase the operating temperature. By combining the aforementioned technologies, this project seeks to demonstrate a cost-effective, high-performance LWIR FPA technology with significantly higher operating temperature and sensitivity than previously attainable, and with the flexibility to meet a variety of Earth Science TIR measurement needs, particularly the special requirements of small satellite missions.