The Nancy Grace Roman Space Telescope project is NASA's next flagship astrophysics mission to study dark energy, dark matter, and exoplanets along with the innumerable topics that will be enabled by the infrared survey telescope's instruments. The Wide Field Instrument contains a focal plane of 18 newly developed Teledyne H4RG-10 HgCdTe detectors. Roman's focal plane completed its first system level thermal vacuum test at NASA Goddard in 2022, when an increase in dark current compared to component level testing was observed for several detectors. Roman chartered an anomaly review board (ARB) and in collaboration with Teledyne undertook a testing program to help identify possible root cause and select from Roman's spare inventory suitable replacement detectors for devices that had significantly degraded. A possible root cause was determined by the ARB along with recommendations for how to prevent further degradation. We summarize the initial observation of the detector anomaly, present the detector testing strategy to find suitable spares and provide evidence of root cause, share the general findings of the ARB, and show new data showing the improved dark current performance.
KEYWORDS: Sensors, Crosstalk, Signal to noise ratio, Signal detection, Field effect transistors, Interference (communication), Resistors, Equipment, Observatories, Cryogenics
The Hawaii-4RG near-infrared detectors offer several output configurations in which the detectors can be interfaced with the European Southern Observatory cryogenic preamplifiers. The buffered mode of output operation has the advantages of higher speed and lower electrical crosstalk between the outputs, reduced unit cell current, etc. One of the effects of the buffered mode operation is increased glow at the bottom of the array due to the operation of the output buffers compared to the unbuffered mode. The excess glow can be a limiting source to achieve low noise in long integrations using the up-the-ramp sampling readout mode. The glow can be significantly reduced by optimally biasing the output buffer stages. This work presents the output buffer glow issue, its quantification in terms of glow per read, glow per unit integration time, its dependency on pixel speed, and its mitigation by optimization of buffered mode operation.
Teledyne Judson Technologies (TJT), a subsidiary of Teledyne Imaging Sensors (TIS), and a TIS team in California have jointly developed a low persistence InGaAs focal plane array (FPA) for use in TIS’s MicroCam SWIR camera. This FPA is built on the Hawaii-1RG (H1RG) read-out integrated circuit (ROIC) which has 1024x1024 pixels with an 18 μm pixel pitch format. Operated at 77 K, the newly developed InGaAs arrays achieve cumulative persistence values of ~0.04-0.08% after 45s of integration. This paper reviews the InGaAs detector design and fabrication processes and FPA test results of low persistence focal plane arrays. The persistence test methodology and test data are also presented. A unique epi-wafer and detector structure was designed to allow for low persistence, low dark current, low bad pixel count, high uniformity, and large reverse bias operation (1.5V). The FPA test data is presented for persistence, dark current, quantum efficiency (QE), and correlated double sampling (CDS) noise, as well as bad pixel count and clusters.
NEO Surveyor is a NASA Planetary Defense Coordination Office mission designed to detect and track >2/3 of potentially hazardous asteroids >140 m in diameter during its 5-year prime mission. NEO Surveyor entered Phase B in June 2021 and is scheduled to launch in 2026 to survey the sky in two infrared bands. The infrared detectors are a key technology for the mission and have been the subject of focused development for more than a decade. In this paper, we report test results for recently produced detectors and describe design elements of the focal plane module relevant to operations for NEO Surveyor.
We describe the design of the cryogenic packaging and testing of the Sensor Chip Electronics (SCE) delivered to the Near-Infrared Spectro-Photometer (NISP) instrument for the ESA Euclid mission. The Euclid mission will observe 15 000 deg2 of extragalactic sky1 from the Sun{Earth Lagrange point L2. The payload of the Euclid spacecraft consists of a telescope with 1.2m SiC primary mirror, passively cooled to ~ 125 K, and two focal plane instruments, the visible instrument (VIS) and NISP. At the heart of the NISP instrument is a 4 x 4 mosaic focal plane of Teledyne H2RG infrared detector arrays held at 100K linked using a cryogenic ex cable (CFC) to the SCE at as low as 130 K. The SCE uses the Teledyne SIDECAR Application Specific Integrated Circuit (ASIC) to provide timing, biases, communications, and data conversion for operation of the HAWAII 2 RG (H2RG) Sensor Chip Assembly (SCA) and interfaces to the NISP warm electronics. The SIDECAR ASIC is mounted onto a Silicon Fanout (SiFO) and Invar table support structure and then wirebonded to a printed wiring board assembly (PWB) with passive components and 91-pin nanoconnectors. The PWB is housed within an enclosure which serves as the mechanical and thermal interface to the NISP Support Structure. The qualification and flight SCE were assembled and subjected to environmental testing at the Jet Propulsion Laboratory and then calibrated and tested with the flight lot SCA and CFC at Goddard Space Flight Centers Detector Characterization Lab. The results of the qualification and reliability tests as well as the measured characteristics of the flight SCE will be summarized.
Near-Earth Object (NEO) Surveyor, a NASA planetary defense space mission, is currently in Phase B with a launch date in 2026. NEO Surveyor is an infrared telescope designed to detect and characterize Potentially Hazardous Asteroids (PHAs). The required sensors leverage the space flight heritage and further development over the last 15 years of HgCdTe arrays to detect infrared light spanning from 4 to 10 μm. NEO Surveyor will employ eight passively cooled HgCdTe Sensor Chip Assemblies (SCAs) across two bands, each band consisting of a 1x4 SCA mosaic to cover a wide field of view. Four of these SCAs have a >5.5 μm cutoff wavelength and cover the shorter 4-5.2 μm (NC1) band, while four SCAs will have a >10.5 μm cutoff wavelength and span the longer 6-10 μm (NC2) band. We present calibration and performance results from two recently produced pathfinder SCAs, one for each band, manufactured by Teledyne Imaging Sensors with development guidance from the University of Arizona, the University of Rochester, and JPL. Both devices demonstrate the requisite low dark current, high well depth, and high quantum efficiency, exceeding mission requirements.
Mark Farris, Majid Zandian, Lisa Fischer, Sam Hoffman, Luis Gordillo, Wyatt Strong, Dennis Edwall, Erdem Arkun, Annie Chen, Eric Holland, Michael Carmody, John Auyeung, James Beletic
The Hawaii-4RG-15 (H4RG-15) Sensor Chip Assembly (SCA) is a 4096×4096 pixel sensor with 15 µm pixel pitch. The H4RG-15 is the newest SCA developed by Teledyne for low light level astronomical applications, providing larger format while retaining the low noise and low power of the H1RG and H2RG arrays with additional new features. The SCAs are currently being produced with mercury cadmium telluride (HgCdTe or MCT) detectors having cutoff wavelengths of 1.7 µm for near-infrared (NIR) and 2.5 µm for short-wave infrared (SWIR) applications. SCAs can also be produced with 5.3 µm cutoff wavelength for mid-wave infrared (MWIR) or optimized for visible only applications with hybrid silicon (HyViSI) detectors. Several science grade detectors have been delivered for use in new astronomical instruments. The H4RG-15 sensor has been developed to enable assembly of mosaics with high pixel fill factor, with a new package design that improves the butt-ability of the SCAs. The new package achieves a high level of flatness and is also appropriate for space flight missions, with assembly using flight qualifiable components.
The detector system for the Euclid Near-Infrared Spectrometer and Photometer (NISP) instrument is a 4×4 mosaic focal plane of 16 H2RG (2K×2K pixels) infrared Sensor Chip Assemblies (SCAs) and 16 SIDECAR ASIC Sensor Chip Electronics (SCE) modules. Teledyne has successfully completed the fabrication, testing, and delivery of 24 sciencegrade flight candidate SCAs to the NASA Jet Propulsion Laboratory (JPL). These SCAs were made with Teledyne’s TRL-9 substrate-removed MBE mercury cadmium telluride (HgCdTe) 2.3 μm cutoff detector material and low-noise H2RG CMOS readout chip. The SCAs are mounted on a buttable molybdenum package that enables close packing of the 16 flight SCAs in the NISP focal plane. In this paper, we present the test results of the 24 Euclid flight candidate SCAs. The key detector performance parameters that are critical to the NISP instrument are: high in-band quantum efficiency with good spatial uniformity, low readout noise, low dark current with tight distribution, low pixel crosstalk, low persistence, and good detector surface metrology profile. All 24 SCAs exceed the Euclid NISP performance and interface requirements. The additional acceptance testing at JPL and NASA Goddard’s Detector Characterization Lab has also been completed. 20 flight SCAs have been delivered to European Space Agency (ESA).
HgCdTe films are grown by molecular beam epitaxy (MBE) on large area CdZnTe substrates to achieve low dark current, high quantum efficiency infrared image sensors with 1.7um and 2.5um cut-off respectively. We present the structural and optical characterization of our HgCdTe films with emphasis on spatial uniformity across 7x7.5cm2 wafer size. Science grade detectors are fabricated on these films and subsequently hybridized to our H4RG-15 4K x 4K readout integrated circuit (ROIC). Test results from these image sensors show low dark current (<0.01e-/pixel/sec), high quantum efficiency across the target spectral range (70-90%), <20e single CDS noise, high operability (>99%), less than 1.0% cross talk and a well capacity larger than 70,000e-. the operation temperature is between 80-110K. These image sensors are also responsive in the visible-IR region due removal of the CdZnTe substrate after hybridization. This feature enables spectrographs to use a single image sensor for both visible and IR regions. These image sensors are developed for extremely large telescopes and used in various telescopes around the world.
The primary goal of the HAWAII 4RG-15 (H4RG-15) development is to provide a 16 megapixel 4096x4096 format at significantly reduced price per pixel while maintaining the superb low background performance of the HAWAII 2RG (H2RG). The H4RG-15 design incorporates several new features, notably clocked reference output and interleaved reference pixel readout, that promise to significantly improve noise performance while the reduction in pixel pitch from 18 to 15 microns should improve transimpedance gain although at the expense of some reduction in full well and possible increase in crosstalk. We report the results of very preliminary characterization of a science grade Phase 2 λc ~ 2.5 μm H4RG-15 operated in both conventional and Interleaved Reference Pixel (IRP) 32-output mode and have demonstrated that the CDS averaged read noise at 200 kHz pixel rate is comparable to, and possibly slightly below, that of the best Phase 1 H4RG-15s. We have also investigated the characteristics of pixels exhibiting RTN in the IRP frames.
In support of the European space agency (ESA) Euclid mission, NASA is responsible for the evaluation of the H2RG mercury cadmium telluride (MCT) detectors and electronics assemblies fabricated by Teledyne imaging systems. The detector evaluation is performed in the detector characterization laboratory (DCL) at the NASA Goddard space flight center (GSFC) in close collaboration with engineers and scientists from the jet propulsion laboratory (JPL) and the Euclid project. The Euclid near infrared spectrometer and imaging photometer (NISP) will perform large area optical and spectroscopic sky surveys in the 0.9-2.02 μm infrared (IR) region. The NISP instrument will contain sixteen detector arrays each coupled to a Teledyne SIDECAR application specific integrated circuit (ASIC). The focal plane will operate at 100K and the SIDECAR ASIC will be in close proximity operating at a slightly higher temperature of 137K. This paper will describe the test configuration, performance tests and results of the latest engineering run, also known as pilot run 3 (PR3), consisting of four H2RG detectors operating simultaneously. Performance data will be presented on; noise, spectral quantum efficiency, dark current, persistence, pixel yield, pixel to pixel uniformity, linearity, inter pixel crosstalk, full well and dynamic range, power dissipation, thermal response and unit cell input sensitivity.
We present the test results of science grade substrate-removed 4K×4K HgCdTe H4RG-15 NIR 1.7 μm and SWIR 2.5 μm sensor chip assemblies (SCAs). Teledyne’s 4K×4K, 15 μm pixel pitch infrared array, which was developed for the era of Extremely Large Telescopes, is first being used in new instrumentation on existing telescopes. We report the data on H4RG-15 arrays that have achieved science grade performance: very low dark current (<0.01 e-/pixel/sec), high quantum efficiency (70-90%), single CDS readout noise of 18 e-, operability >97%, total crosstalk <1.5%, well capacity >70 ke-, and power dissipation less than 4 mW. These SCAs are substrate-removed HgCdTe which simultaneously detect visible and infrared light, enabling spectrographs to use a single SCA for Visible-IR sensitivity. Larger focal plane arrays can be constructed by assembling mosaics of individual arrays.
KEYWORDS: Sensors, Analog electronics, Clocks, Astronomy, Data acquisition, James Webb Space Telescope, Image sensors, Microcontrollers, Array processing, Human-machine interfaces
The SIDECAR ASIC is a fully integrated system-on-a-chip focal plane array controller that offers low power and low noise, small size and low weight. It has been widely used to operate different image sensors for ground-based and flightbased astronomy applications. A key mechanism to operating analog detectors is the SIDECAR ASIC's high level of programmability. This paper gives an overview of the SIDECAR ASIC architecture, including its optimized microcontroller featuring a customized instruction set. It describes the firmware components, including timing generation, biasing, commanding, housekeeping and synchronization of multiple detectors. The firmware development tools including compiler and supporting development environment and hardware setup are presented. The firmware capability for ground-based HxRG applications and for flight-based applications like the James Webb Space Telescope (JWST), the repair of the Advanced Camera for Surveys (ACS), and others are also discussed.
Teledyne’s H2RG focal plane arrays have been widely used in scientific infrared and visible instruments for ground-based and space-based telescopes. The majority of applications use the H2RG with 2.5 micron cutoff HgCdTe detector pixel at an operating temperature of ~77 K (LN2). The exceptionally low dark current of the 2.5 micron H2RG allows for operation at higher temperatures which facilitates simplified instrument designs and therefore lower instrument cost. Performance data of 2.5 micron H2RG arrays at 77K, 100 K, and 120 K are presented and are discussed as a function of detector bias and pixel readout rate. This paper also presents performance data of 1.75 micron and 5.3 micron H2RG focal plane arrays and discusses some of the inherent performance differences compared to 2.5 micron cutoff arrays. A complete infrared camera system that uses the H2RG focal plane array and SIDECAR ASIC focal plane electronics is introduced.
The primary goal of the HAWAII 4RG-15 (H4RG-15) development is to provide a 16 megapixel 4096x4096 format at
significantly reduced price per pixel while maintaining the superb low background performance of the HAWAII 2RG
(H2RG). The H4RG-15 design incorporates several new features, notably clocked reference output and interleaved
reference pixel readout, that promise to significantly improve noise performance while the reduction in pixel pitch from
18 to 15 microns should improve transimpedance gain although at the expense of some degradation in full well and
crosstalk. During the Phase-1 development, Teledyne has produced and screen tested six hybrid arrays. In preparation for
Phase-2, the most promising of these are being extensively characterized in the University of Hawaii’s (UH) ULBCam
test facility originally developed for the JWST H2RG program. The end-to-end performance of the most promising array
has been directly established through astronomical imaging observations at the UH 88-inch telescope on Mauna Kea. We
report the performance of these Phase-1 H4RG-15s within the context of established H2RG performance for key
parameters (primarily CDS read noise), also highlighting the improvements from the new readout modes.
In preparation for the large number of infrared pixels required in the era of Extremely Large Telescopes, Teledyne, in
partnership with the University of Hawaii and GL Scientific, has been funded to develop the next generation of largeformat infrared focal plane array for ground-based astronomy; the 4096 × 4096 pixel (15 micron pitch) H4RG-15. Teledyne has successfully designed, produced, and tested the first generation H4RG-15 prototype arrays. This paper reports on the functionality and performance test results of the H4RG-15 prototypes and provides status of the 2012 pilot production effort.
Yibin Bai, William Tennant, Selmer Anglin, Andre Wong, Mark Farris, Min Xu, Eric Holland, Donald Cooper, Joseph Hosack, Kenneth Ho, Thomas Sprafke, Robert Kopp, Brian Starr, Richard Blank, James Beletic, Gerard Luppino
Teledyne’s silicon hybrid CMOS focal plane array technology has matured into a viable, high performance and high-
TRL alternative to scientific CCD sensors for space-based applications in the UV-visible-NIR wavelengths. This paper
presents the latest results from Teledyne’s low noise silicon hybrid CMOS visible focal place array produced in 4K×4K format with 10 μm pixel pitch. The H4RG-10 readout circuit retains all of the CMOS functionality (windowing, guide
mode, reference pixels) and heritage of its highly successful predecessor (H2RG) developed for JWST, with additional
features for improved performance. Combined with a silicon PIN detector layer, this technology is termed HyViSI™
(Hybrid Visible Silicon Imager). H4RG-10 HyViSI™ arrays achieve high pixel interconnectivity (<99.99%), low
readout noise (<10 e- rms single CDS), low dark current (<0.5 e-/pixel/s at 193K), high quantum efficiency (<90%
broadband), and large dynamic range (<13 bits). Pixel crosstalk and interpixel capacitance (IPC) have been predicted
using detailed models of the hybrid structure and these predictions have been confirmed by measurements with Fe-55 Xray
events and the single pixel reset technique. For a 100-micron thick detector, IPC of less than 3% and total pixel
crosstalk of less than 7% have been achieved for the HyViSI™ H4RG-10. The H4RG-10 array is mounted on a
lightweight silicon carbide (SiC) package and has been qualified to Technology Readiness Level 6 (TRL-6). As part of
space qualification, the HyViSI™ H4RG-10 array passed radiation testing for low earth orbit (LEO) environment.
The development of Hybrid CMOS Detectors (HCDs) for X-Ray telescope focal planes will place them in contention
with CCDs on future satellite missions due to their faster frame rates, flexible readout scenarios, lower
power consumption, and inherent radiation hardness. CCDs have been used with great success on the current
generation of X-Ray telescopes (e.g. Chandra, XMM, Suzaku, and Swift). However their bucket-brigade readout
architecture, which transfers charge across the chip with discrete component readout electronics, results in
clockrate limited readout speeds that cause pileup (saturation) of bright sources and an inherent susceptibility
to radiation induced displacement damage that limits mission lifetime. In contrast, HCDs read pixels with low
power, on-chip multiplexer electronics in a random access fashion. Faster frame rates achieved with multi-output
readout design will allow the next generation's larger effective area telescopes to observe bright sources free of
pileup. Radiation damaged lattice sites effect a single pixel instead of an entire row. Random access, multi-output
readout will allow for novel readout modes such as simultaneous bright-source-fast/whole-chip-slow readout. In
order for HCDs to be useful as X-Ray detectors, they must show noise and energy resolution performance similar
to CCDs while retaining advantages inherent to HCDs. We will report on readnoise, conversion gain, and energy
resolution measurements of an X-Ray enhanced Teledyne HAWAII-1RG (H1RG) HCD and describe techniques
of H1RG data reduction.
Teledyne Imaging Sensors develops and produces high performance silicon-based CMOS image sensors, with associated
electronics and packaging for astronomy and civil space. Teledyne's silicon detector sensors use two technologies:
monolithic CMOS, and silicon PIN hybrid CMOS. Teledyne's monolithic CMOS sensors are large (up to 59 million
pixels), low noise (2.8 e- readout noise demonstrated, 1-2 e- noise in development), low dark current (<10 pA/cm2 at
295K) and can provide in-pixel snapshot shuttering with >103 extinction and microsecond time resolution. The QE
limitation of frontside-illuminated CMOS is being addressed with specialized microlenses and backside illumination. A
monolithic CMOS imager is under development for laser guide star wavefront sensing. Teledyne's hybrid silicon PIN
CMOS sensors, called HyViSITM, provide high QE for the
x-ray through near IR spectral range and large arrays
(2K×2K, 4K×4K) are being produced with >99.9% operability. HyViSI dark current is 5-10 nA/cm2 (298K), and further reduction is expected from ongoing development. HyViSI presently achieves <10 e- readout noise, and new high speed
HyViSI arrays being produced in 2008 should achieve <4 e- readout noise at 900 Hz frame rate. A Teledyne 640×480
pixel HyViSI array is operating in the Mars Reconnaissance Orbiter, a 1K×1K HyViSI array will be launched in 2008 in
the Orbiting Carbon Observatory, and HyViSI arrays are under test at several astronomical observatories. The
advantages of CMOS in comparison to CCD include programmable readout modes, faster readout, lower power,
radiation hardness, and the ability to put specialized processing within each pixel. We present one example of in-pixel
processing: event driven readout that is optimal for lightning detection and x-ray imaging.
In a joint program of Penn State University and Teledyne Imaging Sensors, hybrid CMOS sensors have been developed
for use as X-ray detectors. This detector technology can provide major improvements in performance relative to CCDs,
which are the current standard technology used in the focal planes of X-ray telescopes (e.g. Chandra, XMM, Suzaku, and
Swift). Future X-ray telescope missions are all likely to have significantly increased collection area. If standard CCDs
are used, the effects of saturation (pile-up) will have a major impact, while radiation damage will impact the quality and
lifetime of the detectors. By reading out the hybrid CMOS detector in a pixel-by-pixel fashion at high speeds, with an
energy resolution similar to CCDs, CMOS sensors could increase the range of pile-up free operation by several orders of
magnitude. They are also several orders of magnitude more radiation hard than typical CCDs since they transfer charge
through the thickness of the device, rather than across the length of its surface. Furthermore, hybrid CMOS detectors
can be programmed to read out any variety of windowed regions, which leads to versatility and speed. All of this can be
achieved, in principle, while maintaining the same quantum efficiencies achievable in CCDs. Results of this
development effort and preliminary tests of fabricated detectors will be presented, along with potential applications for
future missions such as EDGE and Constellation-X.
Inter-Pixel capacitance (IPC) is an effect that can occur in bump-bonded hybrid CMOS pixel arrays that employ a source
follower pixel amplifier. IPC can result in the signal in one pixel being sensed by adjacent pixels that are capacitively
coupled. IPC effect is more pronounced in full-depletion silicon hybrid CMOS focal plane arrays than infrared arrays
because of the stronger coupling path through the silicon detector layer. IPC can degrade the image resolution and it can
cause an overestimation of conversion gain (electrons per mV) determined from conventional photon-transfer method
because the IPC "blur" reduces the variance of photon noise. However, the IPC effect can be minimized with
improvements in pixel design, and the conversion gain can be properly calculated, and image resolution can be restored
with deconvolution techniques. In this paper, we report the results of a recent effort to reduce IPC in Teledyne's visible
silicon hybrid CMOS focal plane arrays through pixel design improvements.
Silicon-based hybrid CMOS visible focal plane array technology is emerging as a viable high performance alternative to scientific CCDs. The progress is attributed to the rapid advances in CMOS technology, mature precision flip-chip hybridization of large size and fine pixel arrays, and detector array performance improvements. Its technology readiness level (TRL) for space applications is being enhanced by relevant environmental tests and in-depth characterization of sensor performance. In this paper, we present recent results of Rockwell Scientific's hybrid CMOS silicon focal plane array technology, including large format arrays up to 2048x2048, broadband QE, sensor noise improvement, high radiation hardness, and the higher degree of system integration through on-chip ADCs and companion ASICs.
CMOS-based hybrid silicon focal plane array technology is presented as a high-performance CMOS sensor alternative to CCD technology for future space missions and ground-based telescopes. This paper will discuss the unique performance advantages of the hybrid CMOS arrays, including the very high quantum efficiency from UV to near IR, good spatial resolution at moderate voltage bias, readout commonality with IR detector channels in multi-spectral systems, low noise, low power dissipation, high inherent radiation tolerance, and excellent CMOS functionality afforded by the separately optimized readout circuitry. The ability to retain low noise at high video rates and the fact that CMOS sensors do not suffer the charge transfer efficiency (CTE) degradation of CCDs enable an easy scale-up of CMOS-based FPAs to larger formats without compromising sensor performance. The large hybrid CMOS silicon FPAs up to 2048x2048 format in single chip and 4096x4096 format in mosaic configuration that are demonstrated at Rockwell Scientific will be presented.
The NIRCam instrument will fly ten of Rockwell Scientific’s infrared molecular beam epitaxy HgCdTe 2048x2048 element detector arrays, each the largest available with current technology, for a total of 40 Megapixels. The instrument will have two varieties of MBE HgCdTe, a SWIR detector with λco = 2.5 μm, for the shortwave channel of NIRCam (0.6-2.3 μm); and a MWIR detector with λco = 5.3 μm, for the longwave channel of NIRCam (2.4-5.0 μm). Demonstrated mean detector dark currents less than 0.01 electrons per second per pixel at operating temperatures below 42 K for the MWIR and below 80 K for the SWIR, combined with quantum efficiency in excess of 80 percent and read noise below 6 electrons rms, make these detector arrays by far the most sensitive SWIR and MWIR devices in the world today. The unique advantages of molecular beam epitaxy as well as FPA data on noise, dark current, quantum efficiency, and other performance metrics will be discussed. In addition, the focal plane assembly package designs will be presented and discussed.
This paper discusses the latest technologies for space and ground-based astronomy being pursued by Rockwell Scientific. The discussion covers the latest demonstrated performance of large format NIR (~1.7um cutoff) detectors mated to the HAWAII-2RG readout integrated circuit, our proven readout for large-format arrays for astronomy. Developmental work is presented on the HAWAII-4RG family (consisting of 4k x 4k, 4k x 8k, and 8k x 8k formats), RSC’s newest additions planned to the HAWAII series of astronomy readout integrated circuits. We also present the status of our multifunctional command-and-control ASIC for FPAs, which was first reported at the August 2002 SPIE.
Silicon-based hybrid CMOS focal plane array technology offers many advantages needed for both ground-based and space imaging applications. These advantages include enhanced UV and NIR sensitivity, extensive on-chip readout capability, inherent radiation hardness, flexible imaging readout and the ability to provide extremely low noise at high video rates. For infrared imaging applications that involve UV-through visible channels, the readout electronics commonality facilitates a great simplification to system designs. In this paper, Rockwell Scientific CMOS-based hybrid silicon FPA technology and the recent progress are presented. The hybrid FPAs developed include 640x480, 1024x1024 and 2048x2048 formats with pixel sizes ranging from 27μm to 18μm square, featuring a high optical fill factor (~100%), broad-band response (200nm to 1000nm) with high quantum efficiency, and low read noise (<6e-) that approaches astronomy CCDs at 100KHz video rate and surpasses astronomy CCDs at 1MHz rate. Other performance parameters, such as spatial uniformity, dark current, pixel crosstalk/MTF and CMOS features are also discussed.
The HAWAII-2RG is a major upgrade of our prior 2048 x 2048 CMOS readout for astronomy (HAWAII-2) to support the requirements of the Next Generation Space Telescope and enable breakthrough capability for ground-based astronomy. By migrating to 0.25μm CMOS, for the first time guide mode readout is simultaneously supported in combination with various programmable science modes on a frame-by-frame basis. Consequently, the readout simultaneously supports programmable guide mode window and full-field science using the rest of the 4.2 million pixels at read noise <5 e-. Also for the first time with any imaging sensor, low and high background astronomy is supported using from 1 to 32 low-noise outputs via low-speed and high-speed signal paths. The latter supports throughput rate of up 320 MHz for real time imaging at >60 Hz. As with the HAWAII-2, the readout can be mated to our infrared and visible detector arrays including low dark current MBE HgCdTe at cutoff wavelengths from 1.5μm to 14μm, 2.5μm PACE HgCdTe, and silicon p-i-n detectors with superior quantum efficiency to backside-illuminated CCDs.
The past 2 to 3 years has been a period of explosive growth in technology development for imaging sensors at Rockwell Scientific Co. (RSC). The state of the art has been advanced significantly, resulting in a number of unique advanced imaging sensor products. A few key examples are: 2048 x 2048 sensor chip assemblies (SCA) for ground and space-based applications, 4096 x 4096 mosaic close-butted mosaic FPA assemblies, a very high performance 10 x 1024 hybridized linear SCA for optical network monitoring and other applications, the revolutionary CMOS ProCam-HD imaging system-on-a-chip for high definition television (HDTV), and RSC's near-infrared emission microscope camera for VLSI defect detection/analysis. This paper provides selected updates of these products and thereby provides an overview of the ongoing highly fertile period of technology and product development at Rockwell Scientific. A view into future directions for advanced imaging sensors is also provided.
Silicon-based hybrid CMOS visible focal plane array (FPA) technology is emerging as a strong contender for scientific applications that require broad spectral response with low noise, highly integrated functionality and radiation hardness. CMOS-based FPAs offer many advantages in high speed, low-noise detection and signal processing. As a high performance alternative to advanced CCD imaging arrays, the hybrid design enables independent optimization of the silicon detector array and silicon readout electronics. Multiplexer commonality with the instrument's IR channels is another attractive feature for integrators of sensor sites such as for hyperspectral spectrometers. In this paper, the technical merits of Rockwell's CMOS-based hybrid visible FPAs are described including key detector performance aspects, interface electronics requirements, radiation hardness and concomitant implications for diverse imaging applications. At this time we have developed 640 X 480 and 1024 X 1024 hybrid imagers with approximately equals 100% optical fill factor, high broadband QE spanning ultraviolet (UV) through near infrared (NIR), wide dynamic range, and high pixel operability. Dark current of approximately equals 0.01e-/sec and read noise approximately equals 6e- have been measured on one prototype 1024 X 1024 FPA that uses Hawaii readout integrated circuit (ROIC). Initial radiation data indicate a total ionization dose (TID) tolerance greater than 35 Krad for our standard CMOS process.
Features of the flight hardware version of the NICMOS 256 X 256 mercury-cadmium- telluride (MCT) detector array for the Hubble Space Telescope (HST) are presented and described. Detector flowdown requirements for flight production are reviewed and discussed. Detector cross section and array architecture features are analyzed in relation to quantum efficiency and crosstalk behavior. Features of the charge integration scheme employed are analyzed in assessing dynamic range.
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