Currently advanced MWIR camera systems' shortcomings are related to 1) their high cost and being proprietary to large aerospace companies, 2) their compromise on power or frame rate, and 3) their compromise on noise and well capacity as the pixel pitch goes down and the array size is increased. This paper presents a novel low SWAP-C commercially available high-end MWIR camera system development. The camera incorporates a 10-micron pitch MWIR FPA with a 3-megapixel array size read out at full motion video rate, and even up to 90Hz rate. The small pitch sensor has various gain modes up to 20 million-electron well capacity as well as low noise at high readout rates delivering full 14-bit performance.

The James Webb Space Telescope (JWST) Near Infrared Spectrograph (NIRSpec) incorporates two 5 mu m cutoff (lambda(co) = 5 mu m) 2048 x 2048 pixel Teledyne HgCdTe HAWAII-2RG sensor chip assemblies. These detector arrays, and the two Teledyne SIDECAR. application specific integrated circuits that control theirs, are operated in space at T similar to 37 K. This article focuses on the measured performance of the first flight-candidate, and near-flight candidate, detector arrays. These are the first flight: packaged detector arrays that meet NIRSpec's challenging 6 e(-) rms total noise requirement.

The Wide-field Infrared Survey Explorer is a NASA Midex mission launching in late 2009 that will survey the entire sky at 3.3, 4.7, 12, and 23 microns (PI: Ned Wright, UCLA). Its primary scientific goals are to find the nearest stars (actually most likely to be brown dwarfs) and the most luminous galaxies in the universe. WISE uses three dichroic beamsplitters to take simultaneous images in all four bands using four 1024×1024 detector arrays. The 3.3 and 4.7 micron channels use HgCdTe arrays, and the 12 and 23 micron bands employ Si:As arrays. In order to make a 1024×1024 Si:As array, a new multiplexer had to be designed and produced. The HgCdTe arrays were developed by Teledyne Imaging Systems, and the Si:As array were made by DRS. All four flight arrays have been delivered to the WISE payload contractor, Space Dynamics Laboratory. We present initial ground-based characterization results for the WISE arrays, including measurements of read noise, dark current, flat field and latent image performance, etc. These characterization data will be useful in producing the final WISE data product, an all-sky image atlas and source catalog.

The HAWAII-2RG based focal plane arrays represent one the most advanced imaging sensor technologies for near-infrared and visible astronomy. Since its introduction a few years ago, the HAWAII-2RG has been selected for a large number of space and ground-based instruments, including the James Webb Space Telescope. In addition, the SIDECAR ASIC, a fully integrated FPA controller system-on-a-chip, has been matured and is now being implemented in many of the next generation instruments. As a result of the SIDECAR ASIC, the detector system becomes a fully digital unit that is superior to the conventional discrete focal plane electronics with respect to power consumption, mass, volume and noise immunity. This paper includes an introductory description of the HAWAII-2RG and the SIDECAR ASIC, and presents the latest test results. It also discusses the latest generation of astronomy FPAs: the HAWAII-4RG. This new multiplexer contains all of the HAWAII-2RG features, but provides 4 times as many pixels at a pixel pitch of 10μm. Preliminary HAWAII-4RG test data is presented.

Instruments for large 10-m class telescopes increasingly require high sensitivity large format focal planes. The high spatial resolution achieved with adaptive optics combined with multiple integral field units feeding high resolution spectrographs are driving the pixel performance and require large detector formats. In the infrared spectral range, the array formats have arrived at 2K×2Kpixels with both LPE and MBE grown HgCdTe on CdZnTe substrates. In the optical, fully depleted Si-PIN diodes of the same format are used. The light-sensitive diode arrays are hybridized to CMOS FET switched multiplexers such as the Hawaii-2RG array, which has recently been installed in one of the infrared instruments of the Very Large Telescope (VLT). Basic performance characteristics of the Hawaii-2RG arrays will be discussed such as the noise performance when a special technique of using reference pixels is employed. Larger focal planes are realized as mosaics of 2K×2K arrays. In order to increase the format of single arrays to 4K×4K and larger, the limited substrate sizes make it necessary to reduce the pixel size. However, with smaller pixels the coupling between pixels becomes a limiting factor for the detector point spread function. Fundamental calibration issues relevant to photon transfer techniques of modern CMOS active pixel sensors with special regard to the influence of interpixel coupling capacitances will be analyzed in detail. A novel technique will be presented to directly measure the point spread function generated by the capacitive coupling between adjacent pixels.

The SIDECAR ASIC is a fully integrated FPA controller system-on-a-chip. Compared to conventional control electronics, it requires significantly less power, less space and less weight. The SIDECAR ASIC, which can operate at ambient and cryogenic temperatures, is currently being space-qualified for integration in the science instruments of the James Webb Space Telescope (JWST). This paper gives an overview of the SIDECAR architecture and its supporting drive electronics. It describes the JWST flight configuration including the custom packaging approach. Test results obtained as part of the space qualification effort are presented. CDS noise of the ASIC itself amounts to less than 25 mu V for full 2K x 2K data frames. The noise reduces to less than 6 mu V for up-the-ramp-sampling with 88 frames. Based on the existing qualification results and a number of additional tests in the next few months, NASA Technology Readiness Level 6 (TRL6) will be demonstrated by August 2006.

Advancements in space and ground-based astronomy focal plane array (FPA) technology at Rockwell Scientific Company (RSC) are presented. The review covers the broad base of astronomy work at RSC for both present and next generation FPAs, and details recent achievements in detector, readout, and packaging technologies. RSC astronomy FPA progress includes: RSC FPA delivery for NASA's successful Deep Impact mission, progress on RSC's programs supplying H-2RG FPAs for James Webb Space Telescope (JWST) instruments JWST NIRCam, NIRSpec and FGS; selection of RSC's SIDECAR Application Specific Integrated Circuit (ASIC) for use on JWST instruments NIRCam, NIRSpec and FGS and the development of the JWST SIDECAR space flight package; first silicon on the 16 million pixel HAWAII-4RG (4Kx4K); optimization of NIR FPAs for space telescope missions; construction of multiple 16 million pixel 2x2 mosaic FPAs using the HAWAII-2RG readouts, and the development of the Microlensing Planet Finder (MPF) very large, 150 million pixel FPA.

Traditionally, focal plane arrays require extensive external focal plane electronics (FPE) to provide clocks and biases as well as to digitize the analog output signals. The FPE has to be well-designed and is typically large, heavy and powerhungry. Most importantly, the FPE has to be placed some distance away from the FPA, which complicates maintaining low noise performance throughout the complete system. To offer an alternative to the discrete electronics, Rockwell Scientific has developed a new approach known as the SIDECAR application-specific integrated circuit (ASIC). This single chip provides all the functionality necessary to operate an infrared array with the convenience of a pure digital interface to the outside world. This paper will present performance data on the latest generation of the SIDECAR ASIC operating the JWST H2RG detector arrays at cryogenic temperature. The test results demonstrate that an ASIC based FPA system will meet or exceed all performance requirements for the JWST mission. The SIDECAR ASIC has been selected by NASA to become the FPA drive electronics for all shortwave infrared instruments on JWST.

Growth of Hg 1−x Cd x Te by molecular beam epitaxy (MBE) has been under development since the early 1980s at Rockwell Scientific Company (RSC), formerly the Rockwell Science Center; and we have shown that high-performance and highly reproducible MBE HgCdTe double heterostructure planar p-on-n devices can be produced with high throughput for various single- and multiplecolor infrared applications. In this paper, we present data on Hg 1−x Cd x Te epitaxial layers grown in a ten-inch production MBE system. For growth of HgCdTe, standard effusion cells containing CdTe and Te were used, in addition to a Hg source. The system is equipped with reflection high energy electron diffraction (RHEED) and spectral ellipsometry in addition to other fully automated electrical and optical monitoring systems. The HgCdTe heterostructures grown in our large ten-inch Riber 49 MBE system have outstanding structural characteristics with etch-pit densities (EPDs) in the low 10 4 cm −2 range, Hall carrier concentration in low 10 14 cm −3 , and void density <1000 cm 2 . The epilayers were grown on near lattice-matched (211)B Cd 0.96 Zn 0.04 Te substrates. High-performance mid wavelength infrared (MWIR) devices were fabricated with R 0 A values of 7.2×10 6 Ω-cm 2 at 110 K, and the quantum efficiency without an antireflection coating was 71.5% for cutoff wavelength of 5.21 µm at 37 K. For short wavelength infrared (SWIR) devices, an R 0 A value of 9.4×10 5 Ω-cm 2 at 200 K was obtained and quantum efficiency without an antireflection coating was 64% for cutoff wavelength of 2.61 µm at 37 K. These R 0 A values are comparable to our trend line values in this temperature range.

Burst noise (also known as popcorn noise and random telegraph signal/noise) is a phenomenon that is understood to be a result of defects in the vicinity of a p-n junction. It is characterized by rapid level shifts in both positive and negative directions and can have varying magnitudes. This noise has been seen in both HAWAII-1RG and HAWAII-2RG multiplexers and is under investigation. We have done extensive burst noise testing on a HAWAII-1RG multiplexer, where we have determined a significant percentage of pixels exhibit the phenomenon. In addition, the prevalence of small magnitude transitions make sensitivity of detection the main limiting factor. Since this is a noise source for the HAWAII-1RG multiplexer, its elimination would make the HAWAII-1RG and the HAWAII-2RG even lower noise multiplexers.

The Near-Infrared Spectrograph (NIRSpec) is the James Webb Space Telescope’s primary near-infrared spectrograph. NASA is providing the NIRSpec detector subsystem, which consists of the focal plane array, focal plane electronics, cable harnesses, and software. The focal plane array comprises two closely-butted λco ~ 5 μm Rockwell HAWAII-2RG sensor chip assemblies. After briefly describing the NIRSpec instrument, we summarize some of the driving requirements for the detector subsystem, discuss the baseline architecture (and alternatives), and presents some recent detector test results including a description of a newly identified noise component that we have found in some archival JWST test data. We dub this new noise component, which appears to be similar to classical two-state popcorn noise in many aspects, “popcorn mesa noise.” We close with the current status of the detector subsystem development effort.

Low background applications place the most stringent requirements on detector material, requiring the lowest possible dark currents, highest quantum efficiencies, negligible image persistence (image latency or “ghosts”), high operability, and good uniformity. Rockwell Scientific’s MWIR (λco=5μm) MBE HgCdTe/CdZnTe consistently meets these stringent requirements due to a number of growth techniques unavailable to other MWIR materials. The first part of this paper focuses on the advantages offered by MBE HgCdTe on CdZnTe detectors. The second part focuses on the functional capabilities of our most recent multiplexers, the HAWAII-1RG and HAWAII-2RG. Finally, the paper briefly concludes with a look at the future of SCA control with Rockwell Scientific’s new NGST ASIC for control and digitization of the HAWAII-RG series multiplexers.

The ambitious science goals of the James Webb Space Telescope (JWST) have driven spectacular advances in lambdacosimilar to5um detector technology over the past five years. This paper reviews both the UH/RSC team's Phase A development and evaluation of 2Kx2K arrays exceeding the detector requirements for JWST's near infrared instruments and also the hardware integration of these into a 4Kx4K (16Mpxl) close packed mosaic focal plane array housed in an Ultra Low Background test facility. Both individual first generation 2Kx2K SCA's and 4Kx4K mosaic focal planes have been extensively characterized in the laboratory and, since September 2003, a NIR camera utilizing the 4Kx4K mosaic focal plane has been in use for nearly 100 nights at the UH 2.2 in telescope on Mauna Kea. Typical test results for the first generation 2Kx2K arrays and their integration into 4Kx4K mosaic focal planes are reported. Demonstration of the design concepts and both array and mosaic focal plane performance in actual hardware, as described here, has provided the foundation for design iterations leading to later generations of 2Kx2K arrays and 4Kx4K mosaic focal planes.Four major technology developments leading to first generation hardware demonstrations of both 2Kx2K SCA's and a 4Kx4K mosaic FPA are reviewed. These are: 1) improvement in test equipment and procedures to characterize the detectors against JWST requirements and goals, primarily at 37K but with the capability to test from 30K to 100K; 2) optimization of lambdacsimilar to5um MBE HgCdTe material on a CZT substrate for low dark current (goal of 0.003 e-/sec at 37K) with high quantum efficiency, low cross-talk and greatly reduced image persistence; 3) development of the 2Kx2K HAWAII-2RG multiplexer designed specifically to take full advantage of these detector characteristics for a wide range of astronomical applications ( and fully compatible with an ASIC controller developed under the JWST Instrument Technology Development initiative) and 4) development of molybdenum SCA carriers allowing modules to be close-butted on three sides and easily installed onto a molybdenum plate to form a 4Kx4K mosaic focal plane.We describe both the improvements in the KSPEC test facility and in test procedures for individual 2Kx2K arrays and the Ultra Low Background (ULB) test facility developed specifically to evaluate 4Kx4K mosaic focal plane assemblies required for the NIRCam instrument. The laboratory test configuration of the ULB facility utilizes multiple shields and internal light sources to achieve background fluxes <1 photon/hour per pixel for lambdac-5um while providing temperature stability <1mK over periods of weeks. An alternate configuration utilizes fore optics to allow the mosaic FPA module of the ULB facility to be mounted at the Cassegrain focus of the UH 2.2 meter telescope, providing an image scale of 0.25"/pixel over a 17'x17' field. A cold PK 50 lens cuts off around 1.7um, limiting the background at wavelengths below 1.65um (where the array can be used with normal filters and where narrow band filters reduce the background to levels comparable to NIRCam on JWST). Observations at the teles cope, which provide the best way of verifying certain JWST requirements and allow direct astronomical characterization of the detectors, are reported.

We report on Hg 1−x Cd x Te mid-wavelength infrared (MWIR) detectors grown by molecular-beam epitaxy (MBE) on CdZnTe substrates. Current-voltage (I-V) characteristics of HgCdTe-MWIR devices and temperature dependence of focal-plane array (FPA) dark current have been investigated and compared with the most recent InSb published data. These MWIR p-on-n Hg 1−x Cd x Te/CdZnTe heterostructure detectors give outstanding performance, and at 68 K, they are limited by diffusion currents. For temperatures lower than 68 K, in the near small-bias region, another current is dominant. This current has lower sensitivity to temperature and most likely is of tunneling origin. High-performance MWIR devices and arrays were fabricated with median R o A values of 3.96 × 10 10 Ω-cm 2 at 78 K and 1.27 × 10 12 Ω-cm 2 at 60 K; the quantum efficiency (QE) without an antireflection (AR) coating was 73% for a cutoff wavelength of 5.3 µm at 78 K. The QE measurement was performed with a narrow pass filter centered at 3.5 µm. Many large-format MWIR 1024 × 1024 FPAs were fabricated and tested as a function of temperature to confirm the ultra-low dark currents observed in individual devices. For these MWIR FPAs, dark current as low as 0.01 e − /pixel/sec at 58 K for 18 × 18 µm pixels was measured. The 1024 × 1024 array operability and AR-coated QE at 78 K were 99.48% and 88.3%, respectively. A comparison of these results with the state-of-the-art InSb-detector data suggests MWIR-HgCdTe devices have significantly higher performance in the 30–120 K temperature range. The InSb detectors are dominated by generation-recombination (G-R) currents in the 60–120 K temperature range because of a defect center in the energy gap, whereas MWIR-HgCdTe detectors do not exhibit G-R-type currents in this temperature range and are limited by diffusion currents.

This paper is a review of current astronomy projects at Raytheon/SBRC in the near-infrared (IR) band (optical to 5 mu m). Another paper in this same session (3354-11) covers astronomy projects in longer wavelengths. For ground-based astronomy, InSb arrays with formats of 256 x 256, 512 x 512, and 1024 x 1024 have been developed and tested. For space-based astronomy, four projects are discussed with array formats ranging from 256 x 256 to 2K x 2K. The space projects support instruments on the SIRTF, IRIS, NGST, and Rosetta missions. Representative data are presented from 1024 x 1024 and 256 x 256 arrays obtained by test facilities at NOAO and the University of Rochester.

AIRS is a key instrument in NASA's Earth Observing System (EOS) Program. Passive IR remote sensing is performed using a high resolution grating spectrometer design with a wide spectral coverage focal plane assembly (FPA). The hybrid HgCdTe focal plane consists of twelve modules, ten photovoltaic (PV) and two photoconductive (PC), providing spectral response from 3.7 to 15.4 micrometers. The PV modules use silicon readout integrated circuits (ROICs) joined to the detector arrays as either direct or indirect hybrids. The PC modules are optically chopped and led out to warm electronics. Operating at 58 K, the sensitivity requirements approach BLIP in the critical 4.2 and 15.0 micrometer bands. The optical footprint coupled with the support and interface components of the focal plane make it a very large assembly, 53 mm multiplied by 66 mm. Dispersed energy from the grating is presented to the modules through 17 narrowband filters mounted 0.2 mm above the focal plane in a single, removable precision assembly. With PV and PC devices on the same focal plane operating simultaneously, shielding and lead routing as well as ROIC design have been optimized to minimize any interactions between them. Multilayer carriers have been designed to lead out the closely spaced PC arrays and the entire focal plane itself. Multilayer shielded flex cables are used to interconnect the focal plane to a very unique dewar. The tightly spaced optical pattern, along with more than 50 components in the focal plane, make this a highly complex assembly. The vacuum dewar, while providing approximately 600 leadouts, is directly coupled to the cold spectrometer and operates at 155 K while cooling the focal plane to 58 K via a sapphire rod interfaced to a pulse tube cooler. This paper discusses the key features of the FPA/dewar assembly, modeling/analyses done in support of the design, and results of design validation activities to date.

Higher resolution and wider IR spectral coverage is needed to improved infrared sounding instruments. The Atmospheric Infrared Sounder (AIRS), chosen by NASA to fly on the Earth Observing System, addresses these needs with advanced PV HgCdTe detector arrays designed to cover the spectral range from 3.7 micrometers to 13.6 micrometers with an average resolution of (lambda) /(Delta) (lambda) equals 1200. High performance detectors and advanced readout integrated circuit electronics make it possible to meet mission requirements. For convenience, the AIRS focal plane has been partitioned into four MWIR modules spanning the spectral range from 3.7 micrometers to 8.22 micrometers , and six LWIR modules for wavelengths above 8.8 micrometers . This paper focuses on the AIRS readout device and recent developments in p-on-n heterojunction detector technology at Loral. The detector arrays, operating at 60 K, readily satisfies the requirements of the AIRS instrument. Detector arrays with 4.7 micrometers cutoff wavelength at 60 K and 20 mV reverse bias have RdAs typically greater than 1010 (Omega) (DOT) cm2, with dark signals less than 0.6 fA and detector capacitances less than 0.6 pf for a 50 micrometers by 10 micrometers detector. AR coated MW arrays exhibit quantum efficiencies of greater than 80 percent. Reverse breakdowns are more than -150 mV. Module data for 15.1 micrometers detectors with anti-reflection coating exhibit quantum efficiencies greater than 70 percent and dark currents less than 8 nanoamps at 20 mV reverse bias. Also, excellent module linearity meeting the AIRS stringent requirements is achieved. Of course, measurements of MW detectors require extremely high gain transimpedance amplifiers. The AIRS MWIR readout structures prove to be exceptional in their ability to characterize these high impedance detectors. The charge sensitive input amplifiers on these readout devices utilize an equivalent input integration capacitor of less than 10 fFd to achieve ultrahigh transimpedance gain, and reset noise is suppressed with on focal plane correlated double sampling. LWIR readouts use ultralow noise buffered direct injection preamplifiers. The readouts have a robust architectures with differential input and outputs to minimize EMI and built in redundancy for survivability. Description of the readout device is presented, as well as linearity measurements of both the readout and complete modules.