The Nancy Grace Roman Space Telescope will study the dark matter content of the universe, the expansion history of the universe, and the diversity of exoplanets in the Galaxy using unprecedented wide-field infrared surveys. Roman will accomplish this using a focal plane of 18 newly developed HgCdTe detectors. Roman's detectors, the H4RG-10, are 4 Kx4 K format 10-micron pixel pitch devices manufactured by Teledyne Imaging Sensors. After acceptance testing at the Goddard Detector Characterization Lab, 18 flight detectors were selected for the flight focal plane. Histograms of the performance parameters of the flight detectors are provided and compared against the requirements, deriving yield statistics. The dominant yield loss was read noise (32%) rather than persistence (21%), which may be attributed to the development and use of the PV3 passivation for Roman's sensors. The 18 flight sensors were selected and positioned in the focal plane according to sensor performance in addition to other criteria such as crosshatch and the presence of high total noise and low correlated double sample noise pixels. System-level testing of the focal plane was completed at Goddard in 2023, after which the focal plane was integrated into the Wide Field Instrument (WFI) at BAE Systems (formerly Ball Aerospace). At the end of 2023, the WFI completed its first thermal vacuum test, providing the first instrument-level performance measurements of the focal plane. In the spring of 2024, the WFI completed environmental (vibration and acoustic) testing and finished its second thermal vacuum test before being shipped back to Goddard for integration into the spacecraft assembly. We review the performance of Roman's flight lot of detectors and early results from integration and testing. (c) 2025 Society of Photo-Optical Instrumentation Engineers (SPIE)

The Nancy Grace Roman Space Telescope project is NASA's next flagship a strophysics mission t o s tudy dark energy, dark matter, and exoplanets along with the innumerable topics that will be enabled by the infrared survey telescope's Wide Field Instrument and Coronagraph Instrument. The Wide Field Instrument contains a focal plane of 18 newly developed Teledyne H4RG-10 HgCdTe detectors. The focal plane along with Roman's ASIC for Control And Digitization of Imagers for Astronomy (ACADIA) and the focal plane electronics that power them comprise the focal plane system. Roman's focal plane completed its first s ystem l evel 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 d egraded. A p ossible root c ause was determined by the ARB along with recommendations for how to prevent further degradation. Three detectors were replaced in Roman's focal plane, and results from the following focal plane system thermal vacuum test, implementing recommendations from the ARB, demonstrate improved dark current performance. We summarize the initial observation of the detector anomaly, present the detector testing strategy to find s uitable spares and provide evidence of root cause, share the general findings of the ARB, and show new data showing the improved dark current performance.

Contact resistance can play a significant role in the noise performance of short wavelength infrared (SWIR) focal plane detector arrays (FPAs), particularly during cryogenic operation at low signal backgrounds. For astronomy FPAs, a source follower input cell ROIC is typically used in combination with correlated double sampling (CDS) or a form of up-the-ramp (SUTR) multi-sampling. In this paper, a pixel equivalent circuit model is presented and analyzed by standard techniques. The noise power density spectrum is analyzed for CDS and multi-sampled acquisitions, and it is found that there are three distinct ranges of contact resistance that govern excess noise behavior: the low-noise ROIC-limited range, the intermediate kTC-limited range, and the RC-bandwidth limited case. The model analyses are used to explain FPA data from Teledyne H2RG and H4RG SWIR FPAs. We have found that sampling sequence in combination with contact resistance can influence the total integrated noise, and can explain a FPA failure mode where anomalously low CDS and anomalously high SUTR noise exist in the same region.

We present the test results of science grade 4 K × 4 K HgCdTe H4RG-15 and H4RG-10 SWIR 2.5 μm sensor chip assemblies (SCAs). Teledyne's 4 K × 4 K, 15 and 10 μm pixel pitch infrared arrays are developed for space and era of Extremely Large Telescopes. They are currently being used in new instrumentation on existing telescopes and missions. We report data on H4RG-15 and H4RG-10 arrays that have achieved science grade performance. For H4RG-15 and H4RG-10: very low dark current (<0.005 e − /pixel/s at 80 K and <0.01 e − /pixel/s at 95 K), high quantum efficiency >70–90%, single CDS readout noise <20 e − , operability >99%, total crosstalk <1.5%, well capacity >70 ke − , and power dissipation less than 4 mW are routinely achieved. 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.

We present the test results of science grade 4Kx 4K HgCdTe H4RG-15 and H4RG-10 SWIR 2.5 mu m sensor chip assemblies (SCAs). Teledyne's 4Kx4K, 15 and 10 mu m pixel pitch infrared arrays are developed for space and era of Extremely Large Telescopes. They are currently being used in new instrumentation on existing telescopes and missions. We report data on H4RG-15 and H4RG-10 arrays that have achieved science grade performance. For H4RG-15 and H4RG-10: very low dark current (<0.005 e(-)/pixel/s at 80K and<0.01 e(-)/pixel/s at 95 K), high quantum efficiency >70-90%, single CDS readout noise <20 e(-), operability >99%, total crosstalk <1.5%, well capacity >70 ke(-), and power dissipation less than 4mW are routinely achieved. 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.

The composite image shows highlights of select papers from the Proceedings of the Scientific Detector Workshop 2022. From top left, clockwise : The Euclid NISP Near‐Infrared Focal Plane under test at the CEA/LAM facility in Marseilles, France (see J. Beletic et al ., e230136); The Acuros CQD sensors from SWIR Vision Systems (see C. Mackay, e230104); The Original lab book entry made at Bell Labs by Willard S. Boyle and George E. Smith on October 19th, 1969 (see M.M. Roth, e230066); The focal plane of the Dark Energy Survey (see S.E. Holland, p. xx4); The DECam CCD wafer (see S.E. Holland, e230072); The 2048 × 2048 detector array of JWST NIRCam supplied by Teledyne (see G. Rieke, e230065); Mosaic of three integrated FPA + Linear variable filters (see, J. Beletic et al ., e230136 ). image

Teledyne Imaging Sensors (TIS) is the leading supplier of infrared focal plane arrays (FPAs) to astronomy and TIS plays a strong role in providing image sensors for Earth and Planetary Science. This article starts with a brief introduction to TIS' technologies and image sensor products. We then present some of TIS' deliveries to space missions and ground-based telescopes. The space missions include ESA's Euclid Dark Universe mission and several NASA missions (James Webb Space Telescope, Roman Space Telescope, SPHEREx, EMIT). TIS continues to serve ground-based astronomy by providing the H2RG and the world's largest high-performance infrared astronomy FPA, the H4RG-15, to several ground-based observatories. Active programs will be described. Ongoing work includes NASA's NEO Surveyor asteroid surveillance mission, ESA's Ariel exo-planet spectroscopy mission, and deliveries to the European Southern Observatory's Extremely Large Telescope.

The Wide-Field Infrared Survey Telescope (WFIRST) will answer fundamental questions about the evolution of dark energy over time and expand the catalog of known exoplanets into new regions of parameter space. Using a Hubble-sized mirror and 18 newly developed HgCdTe 4K x 4K photodiode arrays (H4RG-10), WFIRST will measure the positions and shapes of hundreds of millions of galaxies, the light curves of thousands of supernovae, and the microlensing signals of over a thousand exoplanets toward the bulge of the Galaxy. These measurements require unprecedented sensitivity and characterization of the Wide Field Instrument (WFI), particularly its detectors. The WFIRST project undertook an extensive detector development program to create focal plane arrays that meet these science requirements. These prototype detectors have been characterized and their performance demonstrated in a relevant space-like environment (thermal vacuum, vibration, acoustic, and radiation testing), advancing the H4RG-10’s technology readiness level (TRL) to TRL-6. We present the performance characteristics of these TRL-6 demonstration devices.

In 2007, Teledyne presented and subsequently published an empirically derived formula, known as “Rule 07”, for the dark current performance of Mercury Cadmium Telluride (HgCdTe) P-on-n diodes. The Rule 07 metric has become widely popular within the infrared community, not only as a basis for predicting HgCdTe detector and system performance, but as the “number to beat” for other technologies, notably III-V nBn and strained-layer superlattice (SLS) devices. For materials that have sufficiently long recombination lifetimes, HgCdTe being one of the few such widely used materials, internal currents within the detector can be suppressed and the detector becomes limited by the background radiation from the surrounding environment. These currents can be orders of magnitude below Rule 07 and even further orders of magnitude below the Auger-limit. The ability to suppress Auger currents and operate at the radiative limit allows for significantly higher operating temperature and provides several significant advantages, including:  Reduced size, weight, power, cost, and improved reliability associated with reduced cooler requirements  Lower dark current when operating at conventional temperatures, permitting improved sensitivity from lower shot noise and longer achievable integration times Because background radiatively-limited performance is both fundamental and physics-driven, in 2019 we proposed replacing Rule 07 with “Law 19” and provided a comparison of this fundamental limit with Rule 07. In this paper, we review the theoretical performance of Teledyne’s fully-depleted HgCdTe P-υ-N detectors and provide performance data on dark current, dynamic impedance and quantum efficiency (QE) for mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) detectors both at high operating temperatures (up to 300K) and as a function of temperature

State-of-the-art Hg 1− x Cd x Te multilayer structures grown by molecular beam epitaxy on (211)-oriented Cd 1− y Zn y Te substrates have been characterized and their strain and relaxation analyzed. Techniques for measuring lattice mismatch, strain, and crystal quality by measuring symmetric and asymmetric diffraction profiles in different azimuths were adapted and performed in combination with dislocation delineation for full-wafer and multilayer characterization. It was found that the degree of lattice mismatch and in turn the strain state of epitaxial multilayers can be made uniform across full wafers in optimized structures. A strong correlation was revealed between the Zn composition of the Cd 1− y Zn y Te substrates and the crystal quality of the active layers in the multilayer structures. This method can be generalized to optimize multilayer structures to minimize relaxation by the generation of extended defects.

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).

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 review recent advances in the HgCdTe material quality and detector performance achieved at Teledyne using molecular beam epitaxy growth and the double-layer planar hetero-junction (DLPH) detector architecture. By using an un-doped, fully depleted absorber, Teledyne’s DLPH architecture can be extended for use in high operating temperatures and other applications. We assess the potential achievable performance for long wavelength infrared (LWIR) hetero-junction p-lightly-doped n or p-intrinsic-n (p-i-n) detectors based on recently reported results for 10.7 μm cutoff 1 K × 1 K focal plane arrays (FPAs) tested at temperatures down to 30 K. Variable temperature dark current measurements show that any Shockley–Read–Hall currents in the depletion region of these devices have lifetimes that are reproducibly greater than 100 ms. Under the assumption of comparable lifetimes at higher temperatures, it is predicted that fully-depleted background radiation-limited performance can be expected for 10-μm cutoff detectors from room temperature to well below liquid nitrogen temperatures, with room-temperature dark current nearly 400 times lower than predicted by Rule 07. The hetero-junction p-i-n diode is shown to have numerous other significant potential advantages including minimal or no passivation requirements for pBn-like processing, low 1/f noise, compatibility with small pixel pitch while maintaining high modulation transfer function, low crosstalk and good quantum efficiency. By appropriate design of the FPA dewar shielding, analysis shows that dark current can theoretically be further reduced below the thermal equilibrium radiative limit. Modeling shows that background radiation-limited LWIR HgCdTe operating with f/1 optics has the potential to operate within √2 of background-limited performance at 215 K. By reducing the background radiation by 2/3 using novel shielding methods, operation with a single-stage thermo-electric-cooler may be possible. If the background radiation can be reduced by 90%, then room-temperature operation is possible.

If we can make wavelength-sized detectors, we approach the limit at which smaller detectors have no further advantage for imaging focal plane arrays with practical (f/1-2) optics. Of course, this must be accomplished without compromising performance—a challenge for 5- μ m devices for which the perimeter, the currents of which depend on passivation quality, is very large compared with the area of the device. This paper describes the development of small LWIR HgCdTe detectors and compares dark current performance with that of larger basic devices, as described by “Rule 07”, a well-known rule of thumb which gives the HgCdTe dark-current density characteristics of the best reported diodes as a function of device cut-off wavelength and operating temperature. Low cross-talk requires a fully-depleted absorber layer sufficiently thick to provide adequate quantum efficiency (QE). Preliminary results show dark-current densities are more than a factor of ten below the Rule 07 trend line. With these dark-current densities, the measured ∼40% non-anti-reflection-coated QE in the 8–10 μ m region is more than adequate to achieve background-limited performance with the margin under tactical backgrounds for the fast (f/1), diffraction-limited optics required for the small pixels.

We describe progress in the development and demonstration of Teledyne's new high resolution large format FPA for astronomy, the H4RG-10 IR. The H4RG-10 is the latest in Teledyne's HxRG line of sensors, in a 4096x4096 format using 10 micron pixels. It is offered as a hybrid sensor using either a silicon p-i-n detector array (HyViSI) or a HgCdTe photodiode array with standard infrared cutoff wavelength of 1.75 mu m, 2.5 mu m, or 5.3 mu m (with custom cutoff wavelengths also available). The HgCdTe sensor arrays are fully substrate removed to provide high quantum efficiency, response to visible wavelengths, and minimize cosmic ray and fringing mitigation. Packaging using either CE6 or SiC bases is available. Teledyne is currently fabricating H4RG-10 SWIR FPAs for NASA's WFIRST space telescope instrument. Initial array performance has been tested and will be presented. Key results include the demonstration of low dark current (array mean dark current of < 0.01e-/s/pixel at 100K), low noise (< 10 e-/CDS read noise), and high array operability (> 99% pixels). The paper discusses the sensor configuration and features, the performance achieved to date including QE, dark current, noise maps and histograms, and the remaining challenges.

The CHROMA (Configurable Hyperspectral Readout for Multiple Applications) is an advanced Focal Plane Array (FPA) designed for visible-infrared imaging spectroscopy. Using Teledyne’s latest substrateremoved HgCdTe detector, the CHROMA FPA has very low dark current, low readout noise and high, stable quantum efficiency from the deep blue (390nm) to the cutoff wavelength. CHROMA has a pixel pitch of 30 microns and is available in array formats ranging from 320×480 to 1600×480 pixels. Users generally disperse spectra over the 480 pixel-length columns and image spatially over the n×160 pixellength rows, where n=2, 4, 8, 10. The CHROMA Readout Integrated Circuit (ROIC) has Correlated Double Sampling (CDS) in pixel and generates its own internal bias signals and clocks. This paper presents the measured performance of the CHROMA FPA with 2.5 micron cutoff wavelength including the characterization of noise versus pixel gain, power dissipation and quantum efficiency.

Alternate substrates for molecular beam epitaxy growth of HgCdTe including Si, Ge, and GaAs have been under development for more than a decade. MBE growth of HgCdTe on GaAs substrates was pioneered by Teledyne Imaging Sensors (TIS) in the 1980s. However, recent improvements in the layer crystal quality including improvements in both the CdTe buffer layer and the HgCdTe layer growth have resulted in GaAs emerging as a strong candidate for replacement of bulk CdZnTe substrates for certain infrared imaging applications. In this paper the current state of the art in CdTe and HgCdTe MBE growth on (211)B GaAs and (211) Si at TIS is reviewed. Recent improvements in the CdTe buffer layer quality (double crystal rocking curve full-width at half-maximum ≈ 30 arcsec) with HgCdTe dislocation densities of ≤106 cm−2 are discussed and comparisons are made with historical HgCdTe on bulk CdZnTe and alternate substrate data at TIS. Material properties including the HgCdTe majority carrier mobility and dislocation density are presented as a function of the CdTe buffer layer quality.