Paper will present Teledyne's development of high performance Focal Plane Detectors for space Telescopes.

Hyperspectral Thermal Imager (HyTI) is NASA Earth Science Technology Office’s In-space Validation of Earth Science Technologies (InVEST) 2018 funded project to space qualify the strained layer superlattice based Barrier Infrared Detector (BIRD) Focal Plane Array [1] and Fabry-Perot Interferometer amongst other technologies. Its science goal is to monitor the global hydrological cycles and water resources, and develop a detailed understanding of the movement, distribution and availability of water and its variability over time. The heart of the HyTI hyperspectral imager is a 2-dimensional, BIRD FPA designed and developed at JPL. The engineering model of the HyTI instrument was based on a FPA without anti-reflection coating (ARC), which had 24% and 18% quantum efficiency in 8-9.4 m and 8-10.7 m spectral bands respectively at 68K operating temperature. We have deposited a novel nanotechnology based [2] ARC on flight FPA and it produced 31% and 24% quantum efficiency in 8-9.4 m and 8-10.7 m spectral bands respectively at 68K operating temperature. During this presentation we will discuss the development of LWIR BIRD FPAs for the HyTI project.

We demonstrate a full-Stokes integrated polarimeter based on the circular photogalvainc effect in TaAs Weyl semimetal. Our work could enable a new class of compact and broadband polarization sensitive optoelectronic devices.

We report on LWIR multi-stage thermoelectrically cooled cascade photodiodes with InAs/InAsSb superlattice absorbers and contact layers and bulk quaternary wide-gap regions. The aim is to reach high detectivity in conditions where the conventional IR photodiodes suffer from a very low quantum efficiency and extremely low resistances due to a high thermal generation of charge carriers. The heterostructures were grown by MBE on GaAs substrates buffered with GaSb. The connections between stages are made using heavily doped narrow-gap p+/n+ tunnel junctions. The room-temperature detectivities of the devices are close to that of immersed MCT multijunction detectors offered by VIGO (PVMI series).

We report a quantum dot (QD) mid-wave infrared (MWIR) photodetector with an epitaxial regrown Al0.3Ga0.7As layer covering the sidewalls of the MWIR QD infrared photodetector (QDIP). The regrown Al0.3Ga0.7As layer and the InAs/GaAs QD detector materials form a circular heterojunction around the sidewalls of the QDIP. The built-in electric-field (E-field) in the depletion region of the circular heterojunction can drive the electrons away from the sidewall roughness and confine the electrons in the QDIP region. This not only reduces the edge dark current through the sidewalls, but also improves the photo-excited electron collection efficiency by avoiding the traps and non-radiative recombination centers. Bias dependent dark current reduction was observed and is attributed to the biased heterojunction effect. Photocurrent improvement was obtained across the MWIR spectral band. This regrown Al0.3Ga0.7As circular heterojunction technique can be used to improve the performance of high definition MWIR cameras with ultrasmall (i.e. micro- or nano- size) photodetector pixels where the surface to volume ratio is significant.

Novel integration method that addresses thermo-mechanical reliability of the IRFPA hybrid assembly in advanced three-dimensional integration scheme requires optimization by engineering materials used for vertical integration and geometry engineering of the assemblies to be integrated. We present such optimization scheme and applicability of this method to vertical integration of HgCdTe and Type-II Superlattice (T2SL) based IRFPA.

Cryogenic MWIR camera systems have not been readily adopted by commercial new-space applications due to 1) their high cost, size, or power, 2) due to being proprietary to large aerospace companies, or 3) due to the lack of reliability offered by compact commercial MWIR cameras for harsh space environment. This paper presents a novel low SWaP-C commercially available high-end MWIR camera system development for new-space applications. The camera incorporates MWIR FPAs from an 8-micron pitch to a 15-micron pitch, offering mega-pixel formats, and addressing both the scanning and the staring applications. An ASIC chip, that is a companion to the FPA, is utilized to improve both the SWaP-C as well as the reliability of the MWIR imaging camera payload. The architecture is software programmable to readily address a variety of commercial space applications.

Two-color photovoltaic InGaAs infrared (IR) photodetectors with cutoff wavelengths of λc = 1.7 μm and 2.6 μm were monolithically grown on a single substrate by metal-organic chemical vapor deposition. The IR detectors have a back-to-back diode structure with In0.53Ga0.47As (Eg = 0.735 eV) and In0.83Ga0.17As (Eg = 0.488 eV) absorbers with a large lattice-mismatch of ~2%, using step-graded metamorphic InAsxP1-x buffers. The surface roughness and crystal quality of the metamorphic InAsP buffers were investigated by atomic force microscopy and X-ray diffractometry. The InAs0.63P0.37 topmost buffer achieved a low rms surface roughness of 2.8 nm and a sufficient strain relaxation of 97%. Photodetector devices were fabricated with a two-terminal configuration, providing a bias-dependent two-color detection in the short-wavelength IR (SWIR) spectral region (1–3 μm). The dark current densities of the In0.53Ga0.47As diode (blue channel) and In0.83Ga0.17As diode (red channel) were saturated at 1.8×10-8 and 1.1×10-4 A/cm2 at 300 K, respectively. The larger saturated current density in the red channel is due to higher Shockley-Read-Hall recombination and higher intrinsic carrier concentration. The two-color InGaAs detector showed high room-temperature specific detectivities of 4.1×1011 and 3.1×109 cm·Hz1/2/W for the blue (In0.53Ga0.47As) and red (In0.83Ga0.17As) channels, respectively. Our two-terminal InGaAs detector with SWIR two-color detection capability can be easily integrated in commercial two-terminal readout integrated circuits, leading to the realization of high-performance uncooled two-color IR imagers.

As commercial space applications are proliferating there is need for innovative methodology in the design and qualification of infrared cameras. Traditional space qualification plans followed by the aerospace industry are very thorough, but they are too onerous for new-space commercial applications. Cryogenic MWIR camera systems are especially tedious to qualify for the space environment due to 1) MWIR cameras incorporate expensive and delicate FPAs inside a vacuum cryo-housing, 2) they also incorporate expensive cryocoolers that have limited lifetime, 3) their camera electronics needs to be immune to radiation, and 4) the camera assembly must survive launch and must be vacuum compatible. This paper presents a novel approach to design and rapid space qualification of cooled MWIR camera systems. An ASIC chip based built in self-test in the camera simplifies health and status check of the FPA, of the cooler and of the electronics. Smart electronics is incorporated in the camera to automate and highly accelerate various electro-optical tests as well as various space environment qualification tests.

This conference presentation was prepared for the Infrared Sensors, Devices, and Applications XII conference at SPIE Optical Engineering + Applications, 2022.