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 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.

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.

Recent advances in growth of Hg1−x Cd x Te films on large-area (7 cm × 7.5 cm) CdZnTe (CZT) substrates is presented. Growth of Hg1−x Cd x Te with good uniformity on large-area wafers is achieved using a Riber 412 molecular beam epitaxy (MBE) tool designed for growth of Hg1−x Cd x Te compounds. The reactor is equipped with conventional CdTe, Te, and Hg sources for achieving uniform exposure of the wafer during growth. The composition of the Hg1−x Cd x Te compound is controlled in situ by employing a closed-loop spectral ellipsometry technique to achieve a cutoff wavelength (λ co) of 14 μm at 78 K. We present data on the thickness and composition uniformity of films grown for large-format focal-plane array applications. The composition and thickness nonuniformity are determined to be <1% over the area of a 7 cm × 7.5 cm wafer. The films are further characterized by Fourier-transform infrared spectroscopy, optical microscopy, and Hall measurements. Additionally, defect maps show the spatial distribution of defects generated during the epitaxial growth of the Hg1−x Cd x Te films. Microdefect densities are in the low 103 cm−2 range, and void defects are below 500 cm−2. Dislocation densities less than 5 × 105 cm−2 are routinely achieved for Hg1−x Cd x Te films grown on CZT substrates. HgCdTe 4k × 4k focal-plane arrays with 15 μm pitch for astronomical wide-area infrared imagers have been produced using the recently developed MBE growth process at Teledyne Imaging Sensors.

We present the test results of science grade substrate-removed 4Kx4K HgCdTe H4RG-15 NIR 1.7 mu m and SWIR 2.5 mu m sensor chip assemblies (SCAs). Teledyne's 4Kx4K, 15 mu m 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.

The near-earth object camera (NEOCam) is a proposed infrared space mission designed to discover and characterize most of the potentially hazardous asteroids larger than 140 m in diameter that orbit near the Earth. NASA has funded technology development for NEOCam, including the development of long wavelength infrared detector arrays that will have excellent zodiacal background emission-limited performance at passively cooled focal plane temperatures. Teledyne Imaging Sensors has developed and delivered for test at the University of Rochester the first set of approximately 10 mu m cutoff, 1024 x 1024 pixel HgCdTe detector arrays. Measurements of these arrays show the development to be extremely promising: noise, dark current, quantum efficiency, and well depth goals have been met by this technology at focal plane temperatures of 35 to 40 K, readily attainable with passive cooling. The next set of arrays to be developed will address changes suggested by the first set of deliverables. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

We have performed a detailed study of dark current versus voltage to understand existing limitations in dark current and address the nonuniformity of dark current in devices fabricated on HgCdTe grown on silicon substrates. One interesting observation is that trap-assisted tunneling, g-r currents, are not found close to zero bias in certain devices. Devices from the low end of the R 0 A distribution show heavy shunting paths close to zero bias. We believe that these shunting paths may be the limiting cause of tail distributions in fabricated focal plane array tail distributions. Possible causes for these shunting paths are surface charges associated with dislocation cores and impurity gettering at dislocation cores. The measured non-anti-reflection (AR)-coated quantum efficiency (QE) was 0.576 at 78 K and displays the classical response versus wavelength. The measured QE on isolated single devices is consistent with the 256 × 256 focal-plane array mean QE. Obtained average dark currents are on the order of mid 10−5 A cm–2, which is one order of magnitude higher than dark currents obtained from arrays on lattice-matched substrates. On average, arrays on lattice-mismatched substrates show performance characteristics inferior to those of arrays fabricated on lattice-matched substrates. This inferior performance is due to array pixel operability, as can be seen from the tail of the distribution and the average dark currents, which are one order of magnitude higher than those obtained on lattice-matched substrates.

Improved composition control of Hg 1-x Cd x Te layers grown by molecular beam epitaxy using in-situ spectroscopic ellipsometry is described. This has increased our composition yields from <40% to approximately 70% for a specification of x to within 0.0015 of target composition. Knowledge of composition during growth also enables corrections to effusion cell temperatures so that the in-depth composition profile can be controlled. Further improvements were obtained after active composition control was implemented whereby the ellipsometer controls the Te cell temperature to maintain the desired composition.

Very Long Wavelength InfraRed (VLWIR; lambda (c) similar to 15 to 17 mum at 78K) photovoltaic detectors operating in the 78K range are needed for remote sensing applications. This temperature range permits the use of passive radiators in spacecraft to cool the detectors. VLWIR (lambda (c) similar to 15 to 17 mum at 78K) photovoltaic detectors in a range of sizes (8 mum diameter to 1000 mum diameter) have been fabricated and their performance measured as a function of temperature. Molecular Beam Epitaxy (MBE) was used to grow n-type VLWIR Hg1-xCdxTe on lattice matched CdZnTe. Arsenic was implanted and the wafer was annealed to provide the p-type regions. All the material was grown with wider bandgap cap layers and consequently the detector architecture is the Double Layer Planar Heterostructure (DLPH) architecture.I-d - V-d versus temperature curves for 8 and 1000 mum diameter, lambda (c) = 17 mum at 78K detectors indicate that the 8 mum diameter detector is diffusion limited for temperatures greater than 63K even at a -200 mV bias. There is no appreciable tunneling at T = 50K and at -200 mV applied bias. At T = 40K tunneling commences at a bias similar to -80 mV. Below T = 30K, the diode is tunneling limited. The 1000 mum diameter detector is diffusion limited at bias values less than -50 mV at 78K. At zero bias, the detector impedance is comparable to the series/contact resistance. Interfacing with the low (comparable to the contact and series resistance) junction impedance detector is not feasible. Therefore a custom pre-amplifier was designed to interface with the large VLWIR detectors in reverse bias. The detector is dominated by tunneling currents at temperatures less than 78K. The 1000 mum diameter, lambda (c) similar to 17 mum at 78K detectors have dark currents similar to 160 muA at a -100mV bias and at 78K. Detector non-AR coated quantum efficiency > 60% was measured at -100mV bias in these large detectors and the response was constant across the lambda = 7 mum to 15 mum spectral band. With AR-coating the quantum efficiency will be > 70%. Response was measured and non-linearity < 0.15% was calculated for the 1000 <mu>m detectors. The flux values were in the 10(17) ph/cm(2)/sec range and were changed by varying the blackbody temperature. In addition, a linear response was measured while varying the spot size incident on the 1000 mum detectors. This excellent response uniformity measured as a function of spot size implies that, low frequency spatial response variations are absent, for the 1000 mum detectors.

We have developed 1024x1024 HAWAII (HgCdTe Arrays for Wide-field Astronomical Infrared Imaging) focal plane arrays (FPAs) for use in astronomical applications. These devices have been delivered to various astronomy organizations around the world and have resulted in increased sensitivities and decreased observation times for deep space imaging. The detector material is PACE-I for SWIR and Molecular Beam Epitaxy (MBE) HgCdTe on CdZnTe for MWIR. The 1024x1024 multiplexer has a 18.5 mu m unit cell pitch, source follower per detector (SFD) input, and it was fabricated at our internal commercial CMOS process line with excellent yield. Mean dark currents as low as 0.02 e-/s have been measured at 77K for 2.5 mu m devices (1024x1024 format, 18.5 mu m pitch) and 0.39 e-/s for 5.3 mu m devices at 50K (256x256 format, 40 mu m pitch). Quantum efficiencies are >50% for both SWIR and MWIR detectors; with AR coatings, these are expected to be above 75%. Noise levels of 3 e- have been measured by multiple sampling techniques for the SWIR and 75 e- for the MWIR. All of these devices are simple to operate and are readily available. We are presently developing 2048x2048 FPAs with 18 mu m unit cell pitch for both SWIR and MWIR applications.