Proceedings Volume 6660

Infrared Systems and Photoelectronic Technology II

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Proceedings Volume 6660

Infrared Systems and Photoelectronic Technology II

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Volume Details

Date Published: 13 September 2007
Contents: 10 Sessions, 29 Papers, 0 Presentations
Conference: Photonic Devices + Applications 2007
Volume Number: 6660

Table of Contents

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Table of Contents

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  • Multi-Band Focal Planes
  • Infrared Polarimetry
  • Astronomical Application of 2D Arrays
  • QWIP Technology
  • Hyperspectral IR Imaging
  • Special IR System Cameras
  • Silicon Technology
  • Imagers
  • IR Systems
  • Poster Session
Multi-Band Focal Planes
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Foveating infrared image sensors
Nova Sensors, under sponsorship of the Munitions Directorate of the Air Force Research Laboratory, has developed a readout integrated circuit (ROIC) technology for focal plane arrays (FPAs) that permits an intelligent use of the available image data; this is especially effective for dealing with the large volume of data produced by today's large format FPAs. The "Variable Acuity Superpixel Imaging" (VASITM) ROIC architecture allows for coverage of the entire field of view at high frame rates by permitting larger "superpixels" to be dynamically formed on the FPA in regions of relative unimportance, thus reducing the total number of pixel values required to be multiplexed off the FPA. In addition, multiple high-resolution "foveal" regions may be "flown" around the imager's field of view at a frame rate such that high-value targets may be sampled at the highest possible spatial resolution that the imager can produce. Nova Sensors has built numerous camera systems using 320 x 256 and 1K x 1K pixel versions of visible and infrared VASITM FPAs. This paper reviews the technology and discusses numerous applications for this new class of imaging sensors.
Demonstration of a dual-band IR imaging spectrometer
A prototype of a compact, low mass, multispectral imaging spectrometer suitable for space-based applications has been built utilizing a dual-band infrared focal plane array. The spectrometer design uses a grating blaze chosen to be efficient at both 3.75-6.05 and 7.5-12.1 μm. The spectrometer had previously been spectrally calibrated with flooded blackbody illumination and the mercury cadmium telluride focal plane array was found to have cutoff wavelengths near 5.2 and 10.5 μm. The spectrometer was tested in the MWIR band by imaging a blackbody at a distance of 100 m. Spectral images of the Sun were obtained in both MWIR and LWIR, allowing comparison of the solar diameter at various IR wavelengths with tabulated visual widths. The performance of the spectrometer is characterized at a deeper level as a result of these observations.
3D simulation of detector parameters for backside illuminated InSb 2D arrays
Tal Fishman, Vered Nahum, Erez Saguy, et al.
Accurate and reliable numerical simulation tools are necessary for the development of advanced semiconductor devices. SCD is using the Silvaco Atlas simulation tool to simultaneously solve the Poisson, Continuity and transport equations for 3D detector structures. In this work we describe a set of systematic experiments performed in order to calibrate the Atlas simulation to SCD's backside illuminated InSb focal plane arrays (FPA) realized with planar technology. From these experiments we extract physical parameters such as diffusion length, surface recombination velocity, and SRH lifetime. The actual and predicted performance (e.g. dark-current and MTF) of present and future detectors is presented. We have studied arrays with pitch in the range of 15 to 30 μm. We find that the MTF width is inversely proportional to the pitch. Thus, the spatial resolution of the detector improves with decreasing pixel size as expected. Using the Atlas simulation we predict the performance of planar InSb arrays with smaller pixel dimensions, e.g., 12 and 10 μm.
Infrared Polarimetry
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A survey of infrared polarization in the outdoors
This paper provides a summary of the principles that combine to create the infrared polarization signature of an object viewed in the outdoor environment. The primary variables discussed here include polarized emission and reflection from the source (object of interest). Because the observed polarization signature arises from a combination of mutually orthogonally polarized emitted and reflected radiance components, the background radiance is an important variable to consider in many infrared imaging situations. Examples are shown of polarization spectra calculated for a smooth dielectric surface viewed under atmospheric conditions ranging clear and dry to cloudy. As long as the object of interest is radiometrically warmer than the background (sky in this case), the observed radiance is partially p-polarized, but the degree of polarization varies with the magnitude of the reflected radiance.
Development of a MWIR polarimetric FPA
David P. Forrai, Darrel W. Endres, John W. Devitt, et al.
Past work with polarimetry in the mid-wave infrared (MWIR) has yielded mixed results. In order to better characterize polarimetric content in the MWIR and short-wave infrared (SWIR) atmospheric windows, we are developing focal plane array (FPA) technology that will address shortcomings in earlier devices. In particular, our efforts are focusing on placing micro-polarizing grids in very close proximity to the P-N junction of the detector. By placing these micropolarizers very close to the photodetector junction, the opportunity for polarimetric cross talk between pixels is minimized. CE's unique process for fabricating FPAs is well suited for implementing this approach. Since a polarimetric FPA consisting of a standard FPA and micro-wire grid polarizers reduces the effective FPA format by a factor of two in both dimensions, the ability to produce extremely large format FPAs are critical to obtain high resolution polarimetric imagery. CE's FPA fabrication process is also highly scalable and has successfully fabricated FPAs as large as 2k by 2k. This paper describes the progress we've made towards developing these unique polarimetric FPAs.
Longwave infrared snapshot imaging spectropolarimeter
A very unique imaging spectopolarimeter for use in the long wave infrared, 8 to 12 microns, is currently being constructed. The imaging system uses a novel technique first developed at the University of Arizona, which incorporates channeled spectropolarimetry with a computed tomographic imaging spectrometer (CTIS). The system is especially noteworthy because it contains no moving parts and operates in a snapshot mode, allowing it to record spectral data as well as the polarization state of each wavelength band in the spectra from every spatial location in a 2D image in a single integration period. The paper presents results from the currently constructed longwave infrared snapshot imaging spectrometer, as well as a description of what will be added to the system to obtain polarization data, and an overview of the design and operational details of the snapshot imaging spectropolarimeter.
Astronomical Application of 2D Arrays
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High performance large infrared and visible astronomy arrays for low background applications: instruments performance data and future developments at Raytheon
Raytheon Vision Systems (RVS) has developed a family of high performance large format infrared detector arrays for astronomy and civil space applications. RVS offers unique off-the-shelf solutions to the astronomy community. This paper describes mega-pixel arrays, based on multiple detector materials, developed for astronomy and low-background applications. New focal plane arrays under development at RVS for the astronomy community will also be presented. Large Sensor Chip Assemblies (SCAs) using various detector materials like Si:PIN, HgCdTe, InSb, and Si:As IBC, covering a detection range from visible to large wavelength infrared (LWIR) have been demonstrated with an excellent quantum efficiency and very good uniformity. These focal plane arrays have been assembled using state-of-the-art low noise, low power, readout integrated circuits (ROIC) designed at RVS. Raytheon packaging capabilities address reliability, precision alignment and flatness requirements for both ground-based and space applications. Multiple SCAs can be packaged into even larger focal planes. The VISTA telescope, for example, contains sixteen 2k × 2k infrared focal plane arrays. RVS astronomical arrays are being deployed world-wide in ground-based and space-based applications. A summary of performance data for each of these array types from instruments in operation will be presented (VIRGO Array for large format SWIR, the ORION and VISTA Arrays, NEWFIRM and other solutions for MWIR spectral ranges).
VIS/SWIR focal plane and detector development at Raytheon: instruments performance data and future developments at Raytheon
Jonathan Getty, Ellie Hadjiyska, David Acton, et al.
Raytheon has developed SWIR and Visible-SWIR Focal Plane Arrays (FPAs) with over one million pixels that meet the demanding requirements of astronomy, night vision, and other low background systems. FPA formats are 1280 × 1024, 1024 × 1024 and 2048 × 2048, with detector elements on 20 μm pitch. This paper describes recent results on SWIR HgCdTe detectors, low-noise Readout Integrated Circuits (ROICs), and FPA imaging. SWIR HgCdTe detectors have been fabricated with cutoff wavelengths of 1.7 and 2.5 μm and have demonstrated high quantum efficiency and flat spectrals, including visible response to 400 nm. We compare InGaAs and HgCdTe detectors, and show HgCdTe passivation improvements which increase carrier lifetime fourfold over existing processes
QWIP Technology
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Toward 16 megapixel focal plane arrays
S. D. Gunapala, S. V. Bandara, J. K. Liu, et al.
Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 1024x1024 pixel InGaAs/GaAs/AlGaAs based quantum well infrared photodetector (QWIP) focal planes have been demonstrated with excellent imaging performance. The MWIR QWIP detector array has demonstrated a noise equivalent differential temperature (NEΔT) of 17 mK at a 95K operating temperature with f/2.5 optics at 300K background and the LWIR detector array has demonstrated a NEΔT of 13 mK at a 70K operating temperature with the same optical and background conditions as the MWIR detector array after the subtraction of system noise. Both MWIR and LWIR focal planes have shown background limited performance (BLIP) at 90K and 70K operating temperatures respectively, with similar optical and background conditions. It is well known that III-V compound semiconductor materials such as GaAs, InP, etc. are easy to grow and process into devices. In addition, III-V compound semiconductors are available in large diameter wafers, up to 8-inches. Thus, III-V compound semiconductor based infrared focal plane technologies such as QWIP, InSb, and strain layer superlattices (SLS) are potential candidates for the development of large format focal planes such as 4096x4096 pixels and larger. In this paper, we will discuss the possibility of extending the infrared detector array size up to 16 megapixels.
Far infrared and terahertz quantum well intra-subband photodetector (QWISP)
David Z.-Y. Ting, Yia-Chung Chang, Sumith V. Bandara, et al.
We describe a new device concept for far infrared (FIR) / terahertz (THz) radiation detection based on the use of dopant-assisted intra-subband absorption mechanism in quantum wells. We compare the Quantum Well Intra-Subband Photodetector (QWISP) to the FIR/THz quantum-well infrared photodetector (QWIP) and heterojunction internal photoemission (HIP) devices to clarify the device concept. We demonstrate QWISP's effectiveness through theoretical simulations by comparing it with the FIR/THz QWIP with comparable dark current levels and peak spectral positions. In particular, our modeling results show that in a device designed for ~110 μm peak response, the QWISP peak absorption coefficient and responsivity, respectively, are approximately 100 and 10 times strong than those for the FIR/THz QWIP. The QWISP is a compact device with normal incidence response, does not require very low barriers, and is compatible with existing GaAs focal-plane array technology.
LWIR QWIP focal plane array mounting with cryogenic optical system
William R. Johnson, Sarath Gunapala, Jason Mumolo, et al.
We present progress on developing a mechanical and thermal isolation package for maintaining multi-stage temperature control for various parts of a dewar package. Our long-wave QWIP focal plane is maintained at 40K while our optics package, which is at close proximity (~2mm) to the FPA, is maintained at 80K. Radiative baffling is controlled at acceptable levels using high conductance heat sinks, while conductance loads are minimized using proper insulating materials (polyimide synthetics) in combination with materials to preserve high structural stiffness (titanium, invar). Furthermore, the optics package is held at low cryogenic temperatures only ~ 6mm from the ZnSe dewar window. An effort is made to keep the complete electro-optical system at these low temperatures independently using only a single 10W low EM-noise closed cycle cryocooler. Proper geometry is defined which takes into account thermal symmetries and mechanical structural stability, while maintaining the necessary external 300K heat sinks. Both conductance and radiative loading on the opto-mechanical structure are examined using finite element analysis and proper heat sinking is established to thermally isolate the optics within the dewar jacket while maintaining proper structural stability. A custom LCC is designed which maximizes the thermal expansion budget between the FPA and optics package, while necessary structural mounting of the electronics boards are coupled with the dewar coldfinger.
MBE grown type-II superlattice photodiodes for MWIR and LWIR imaging applications
Cory J. Hill, Jian V. Li, Jason M. Mumolo, et al.
We report on the status of GaSb/InAs type-II superlattice diodes grown by molecular beam epitaxy (MBE) and designed for infrared absorption in the 2-5μm and 8-12μm bands. Recent LWIR devices have produced detectivities as high as 8x1010 Jones with a differential resistance-area product greater than 6 Ohmcm2 at 80K with a long wavelength cutoff of approximately 12μm. The measured quantum efficiency of these front-side illuminated devices is close to 30% in the 10-11μm range. MWIR devices have produced detectivities as high as 8x1013 Jones with a differential resistance-area product greater than 3x107 Ohmcm2 at 80K with a long wavelength cutoff of approximately 3.7μm. The measured quantum efficiency of these front-side illuminated MWIR devices is close to 40% in the 2-3μm range at low temperature and increases to over 60% near room temperature. Initial results on SiO2 and epitaxial-regrowth based passivation techniques are also presented, as well as images from the first lot of LWIR arrays.
Hyperspectral IR Imaging
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SWIR variable dispersion spectral imaging sensor
F. D. Shepherd, J. M. Mooney, T. E. Reeves, et al.
A novel spectral imaging sensor based on dual direct vision prisms is described. The prisms project a spectral image onto the focal plane array of an infrared camera. The prism set is rotated on the camera axis and the resulting spectral information is extracted as an image cube (x, y, λ), using tomographic techniques. The sensor resolves more than 40 spectral bands (channels) at wavelengths between 1.2 μm and 2.5 μm wavelength. The sensor dispersion characteristic is determined by the vector sum of the dispersions of the two prisms. The number of resolved channels, and the related signal strength per channel, varies with the angle between the prism dispersion axes. This is a new capability for this class of spectral imaging sensor. Reconstructed short-wave imagery and spectral data is presented for field and laboratory scenes and for standard test sources.
The spaceborne infrared atmospheric sounder for geosynchronous Earth orbit (SIRAS-G): pathfinder to space
The Spaceborne Infrared Sounder for Geosynchronous Earth Orbit (SIRAS-G) was developed by Ball Aerospace and Technologies Corp (BATC) under NASA's 2002 Instrument Incubator Program. SIRAS-G is a technology development program focused on next-generation IR imaging spectrometers for sounding of the atmosphere. SIRAS-G is ideally suited for measuring atmospheric temperature and water vapor profiles, trace gases concentrations, land and ocean surface temperatures and the IR mineral dust aerosol signature from satellite, providing high-spectral resolution imaging spectroscopy over a broad IR spectral range and extended field of view. Instrument concepts for future mission in LEO and GEO are discussed, including an instrument concept to be flown in low earth orbit having the potential to provide high spatial resolution, comparable to that of MODIS, along with the high spectral resolution currently being demonstrated by the Atmospheric Infrared Sounder (AIRS). This capability would dramatically improve the yield of cloud-free pixels scenes that can be assimilated into Numerical Weather Prediction (NWP) models. The SIRAS-G dispersive spectrometer module is readily adaptable for missions in LEO, GEO and MEO orbits and can be optimized for spectral resolution over subsets of the total spectral range. We have completed the 3-year SIRAS-G IIP development effort, including successful testing of the SIRAS-G laboratory demonstration spectrometer that utilized the Hawaii 1RG MWIR FPA. Performance testing was conducted at cryogenic temperatures and the performance of the demo instrument has been quantified including measurement of keystone distortion, spectral smile, MTF, and the spectral response function (SRF) to high accuracy. We present the results of the laboratory instrument development including characterization of the demonstration instrument performance. We discuss instrument concepts utilizing SIRAS-G technology for potential future missions including an anticipated airborne flight demonstration.
Special IR System Cameras
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VLIWR HgCdTe staring focal plane array development
James Stobie, Allen Hairston, Steve Tobin, et al.
Atmospheric remote-sensing have been one of the primary drivers toward longer wavelength infrared sensors beyond the 8 to 12 um atmospheric window typically used for terrestrial imaging systems. This paper presents the recent performance improvement attained with very long wavelength infrared (VLWIR) focal plane arrays, by the stringent control of the small bandgap HgCdTe material quality. Array operability is further enhanced by design using a 2:1 super-pixel detector format scheme with programmable bad element de-select and our new detector input offset optimization circuitry within each unit cell. Focal plane arrays with peak quantum efficiencies in excess of 80 percent, and cutoff wavelengths out to 15 μm have NEI operabilities around 95 percent for mid 1014 ph/s-cm2 fluxes operating near 50 K. Average NEI of 3.5 x 1010 ph/s-cm2 was demonstrated for a 14 μm cutoff wavelength focal plane array, consisting of over 55,000 elements, operating with an effective sample time of 87.5 ms.
Mid-IR photon counting array using HgCdTe APDs and the Medipix2 ROIC
John Vallerga, Jason McPhate, Larry Dawson, et al.
We present the design of an infrared (IR) photon counting array consisting of an array of mid IR HgCdTe APDs read out with a CMOS application specific integrated circuit (ASIC) developed for x-ray imaging called the Medipix2. The Medipix2 is an array of 256x256 pixels, each of which amplifies and counts pulse events. When combined with an APD whose gain is high enough, the Medipix2 will integrate these detected photons, and the binary readout of these counters will be fast (~ 1kHz framerate) and noiseless. Initial feasibility tests of this concept using individual APDs from DRS technologies Inc. wirebonded to Medipix input pads are discussed.
Silicon Technology
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Noise suppression with distributed sensing concept FPA DISCO architecture
Low frequency noise, multiplicative noise and background are distinctive features of modern IR FPA. Background subtraction, frame averaging and adaptive thresholding are conventionally used to improve IR sensor performance by adaptively separating valid exceedances from the background and noise. However, the technique may not fully address the problem - neither for fast nor for slow changes in the background and noise. Probability of target detection as well as efficiency of digital video-signal processing can be dramatically increased by effective noise and signal management. Recursive Adaptive Frame Integration of Limited data (RAFIL) was proposed to reduce data rate while maintaining low False Alarm Rate. Distributed Sensor concept - DISCO was proposed for the SNR and target acquisition range increase through cooperative target engagement. In this paper a combination of those two techniques is discussed with the intention to minimize low frequency noise, the background and multiplicative effects in FPA based IR and optical sensing.
Development of a Si:As blocked impurity band detector for far IR detection
Deniz S. Tezcan, Jan Putzeys, Koen De Munck, et al.
This paper reports on the fabrication and characterization of a linear array of Blocked Impurity Band (BIB) far infrared detectors and of the related Cryogenic Readout Electronics (CRE). It is part of the ESA DARWIN project which aims at the study of exoplanets by means of null interferometry and requires high performance infrared detector arrays in the 6 18μm range. Si:As BIB detectors have been fabricated on an infrared transparent Silicon substrate enabling backside illumination. The buried contact, the active and the blocking layers are deposited by epitaxy; the doping profile is controlled by adjusting the growth parameters. Access to the buried contact is provided by anisotropic silicon etch of V-grooves in the epi layers. Spray coating of photoresist is used for the lithography of the wafers with high topography. The CRE is composed of an input stage based on an integrating amplifier in AC coupled feedback with selectable integrator capacitors, of a sample and hold stage which provides isolation between input and sampling capacitance, and of an output buffer with multiplexing switch. The readout is optimized for low noise with minimum operating temperature of 4K. Linear arrays made of 42 and 88 detectors and having 30μm pixel pitch with various active areas are fabricated. Detector arrays are coupled to the CRE by Indium bumps using flip-chip technology. Measurements on the readout show reduced noise, good linearity and dynamic range. First detector characterization results are presented.
Focal plane detectors for the WISE 12- and 23-µm bands
H. H. Hogue, R. B. Mattson, M. G. Stapelbroek, et al.
DRS Sensors & Targeting Systems, under contract to the Space Dynamics Laboratory of Utah State University, is providing the focal plane detector system for NASA's Wide-field Infrared Survey Explorer (WISE). The focal plane detector system consists of two mercury cadmium telluride (MCT) focal plane module assemblies (FPMAs), two arsenic doped silicon (Si:As) Blocked Impurity Band (BIB) FPMAs, electronics to drive the FPMAs and report digital data from them, and the cryogenic and ambient temperature cabling that connect the FPMAs and electronics. The MCT and Si:As BIB focal plane arrays (FPAs) utilized in the WISE FPMAs are both megapixel class indium-bump hybridized devices fabricated by Teledyne Imaging Systems and DRS Sensors & Targeting Systems, respectively. This paper reports performance of the WISE Si:As BIB FPAs that are used for the WISE 12- and 23-μm wavelength bands.
Imagers
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CMOS pixel structures optimised for scientific imaging applications
Thomas Greig, Andrew Holland, David Burt, et al.
In this paper we present the results from a pilot project at e2v technologies to examine the performance of CMOS Active Pixel Sensors for scientific applications. We describe the characterisation of two prototype 128 × 128 pixel imaging devices with scanning circuitry, as well as 5 × 5 pixel test structures with further variation in pixel design. The main variation in the design is the type of photodiode. In this process two types of diode were available, a 'shallow' n+/p-well diode and 'deep' n-well/p-substrate diode. The characterisation includes the use of photon transfer curves to measure output responsivity and we quantify dark signal variations between pixel structures and reset noise levels. A source of additional dark signal is found to be light emission from the in-pixel transistors. We also present results from an optical characterisation of the stand alone devices, including QE response, MTF and PSF measurements. Finally we outline the considerations to produce such a device using a more advanced process with a smaller feature size.
Nearsighted photodetector and camera
Mitsuharu Matsumoto, Yoshifumi Buyo, Shuji Hashimoto
This papar proposes an optical camera which detects not the distant objects but the close objects, namely Nearsighted camera. In general, the optical camera can detect not only the close object but also the distant objects located in front of the camera. However, when we consider some tasks for the robots such as the obstacle avoidance and the object holding, the distant objects sometimes interfere the task executions. The procedures may become easier if the robot can detect only the close objects related to the tasks. Although there are some studies about the object recognition utilizing the difference of the distance from the camera to the objects such as depth from (de)focus and stereo vision, the computational cost is large. The authors, therefore, focus on close object detection and aim at developing an optical camera for close object detection. Though there are some active devices for detecting the close object such as ultrasonic distance sensor and infrared radiation sensor, there are few passive devices for the close object recognition. We explain the design method of the fundamental devices in the nearsighted camera, and show the prototype of the nearsighted camera. To evaluate the features of nearsighted camera, we conduct the experiments for confirming the performance of the fundamental device in the nearsighted camera. We also conduct the experiments for detecting some characters in near field. The experimental results show that nearsighted camera reacts not to the distant objects but to the close objects.
Dark current reduction of GaInAsSb based photodetectors by surface treatment with octadecylthiol
Y. G. Xiao, V. Bhagwat, I. Bhat, et al.
In this work, we report dark current reduction, which is achieved by surface treatment with Octadecylthiol (OTD), for GaInAsSb based photodetectors. Epitaxial layers of the GaInAsSb photodetector were grown on n-type GaSb substrates with a horizontal MOCVD reactor, and the devices were fabricated by wet chemical etching. Surface treatment was carried out by immersing fresh-prepared detector samples in molten ODT solution maintained at 100 °C for 5 hours. The ODT treated devices show an order of magnitude reduction in the leakage current density in comparison with the untreated devices. The inverse of the dynamic zero bias resistance area product (1/R0A) is also lower for ODT treated devices. XPS analyses indicate the formation of Ga-S (20.1 eV) and In-S (445.3 eV) bonds at the surface and reduction in the formation of native oxide on ODT treated GaInAsSb surface. This means that surface treatment with ODT can effectively passivate dangling bonds and also reduce the native oxide. These results indicate that ODT can be used for an effective passivation technique when more sophisticated processing steps are further developed.
IR Systems
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Hg1-xCdxTe mid-wavelength infrared (MWIR) avalanche photodiode (APD) grown on Si substrate
Photodetectors with high bandwidth and internal gain are required to detect highly attenuated optical signals for defense application and long distance communication. IR avalanche photodiodes (APDs) are best suited for this purpose due to their internal gain-bandwidth characteristics coupled with long range data transmission capability. For the past two decades, HgCdTe has been the most successful material for infrared photodetector applications. Recent advances in epitaxial growth techniques made possible the growth of advanced HgCdTe APD structures, but to the best of our knowledge all are grown on expensive substrates (e.g. CdZnTe, CdTe). We report for the first time HgCdTe-based MWIR (4.5 μm) p-i-n APD grown on Si substrate by molecular beam epitaxy (MBE). The devices were fabricated by 365nm UV photolithography and wet-etching technique. The diode had a junction area of 300μm diameter. The R0A of the diode was 3 x 106 Ω-cm2 at 77K. Multiplication gains of 800 were measured at a reverse bias of 10 V in the linear operation regime. The gain increased exponentially as the reverse bias was increased, indicating that only one carrier is responsible for the impact ionization. Temperature dependence of the multiplication gain and of the breakdown voltage further confirms that avalanche multiplication dominates high reverse bias I-V characteristics.
Study on the effective method to reduce the lens calibre of the un-cooled IR thermal imaging systems
During the development of the research and the manufacture technical, the Infrared thermal imaging systems has developments advance rapidly. And its applied field has going deep into the space technology, industry, agriculture, medical, traffic and other fields from the national defense and military appliance. Especially in the application of the military, it has come into being a specialty IR System Engineering field. But in many important applications, the lens calibre of the IR thermal imaging systems often be made very large to advance the SNR of the systems. This increased the weight and the research cost of the whole system very much. Many research indicated that the main factor to affect the image quality of the IR systems is the fixed pattern noise (FPN) or spatial non-uniformity under the actual technical and manufacture level. If we using the effective dynamic self-adaptive non-uniformity correction algorithms for the IR system, and use the image enhancement technology simultaneity. We can advance the imaging quality greatly. With this plan, the correction image we got with large F number can receive the level that uncorrected image with 1 or 2 smaller F number. It means the lens calibre of the system will be reduced effectively. And the weight, the cubage and the research cost of the system will be reduced greatly. It will have most important value in the applied of the actual engineering.
Corrugated QWIP developments for tactical infrared imaging
David P. Forrai, Kwong-Kit Choi, John W. Devitt
The corrugated quantum well infrared detector (C-QWIP) offers improvements to quantum efficiency and spectral bandwidth compared to current commercial QWIPs. In addition to improved performance, the C-QWIP also uses manufacturing processes that are mature and low cost. Thus, very large format focal plane arrays (FPAs) can be fabricated with high yield. There are two applications where the C-QWIP can provide cost effective solutions. The first is very large format long-wave infrared (LWIR) sensors. Most very large format FPAs operate in the mid-wave infrared (MWIR). The MWIR band has significantly lower flux than LWIR, therefore in situations where the backgrounds are cold or there is potential motion blur, the LWIR C-QWIP offers better performance. The second application is two-color registered high-resolution wide area imagery. ARL and CE have been developing both C-QWIP detectors and read-out integrated circuits to support these needs. This paper describes the progress we've made in developing high conversion efficiency LWIR C-QWIP FPAs and MWIR/LWIR two-color FPAs and our path forward to multimegapixel C-QWIP FPAs and sensors.
Poster Session
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Considerations concerning an image transceiver system design
Nonel Thirer, Yitzhak David, I. Baal Zedaka, et al.
In this presentation, several options for implementing an Image Transceiver System operating in real time are analyzed. These include: the implementation of a multi chip system (including Display, Imager and Controller/Processor chips) versus a single chip embedded system. The logical and physical aspects of a single chip, two chip- and three chip-implementation are analyzed. The parallel and serial data transfer methods are analyzed for each case.
Experimental data on the reflection and transmission spectral response of photocathodes
R. J. Brooks, J. R. Howorth, K. McGarry, et al.
The spectral transmission and electron emissivity responses, measured for a series of typical photocathodes, are presented and analysed. Specifically, samples of S1, S20, S25, Bialkali and two types of solar-blind telluride photocathodes were investigated in both transmission and reflection modes of operation. The transmission mode is more convenient for imaging, night vision and for scintillation counting applications such as CT scanners and is more commonly used than the reflection mode. However, more recent work has focussed on the reflection photocathode as a source of electrons with low energy spread used for electron guns for microscopy and lithographic free electron lasers [1]. Our analysis provides a determination of the reflectivity of the substrate/cathode and cathode/vacuum interface, enabling the refractive index to be deduced. The high apparent quantum efficiency (QE) of some conventional photocathodes is shown to be due to the conversion of each photon to two or more electrons.
Modeling of resonant cavity enhanced separate absorption charge and multiplication avalanche photodiodes by Crosslight APSYS
Y. G. Xiao, Z. Q. Li, Z. M. Simon Li
Based on the advanced drift-diffusion simulator, the Crosslight APSYS, InGaAs/AlGaAs resonant cavity enhanced separate absorption charge and multiplication APDs for high bit-rate operations have been modeled. The APSYS simulator is based on drift-diffusion theory with many advanced features. Basic physical quantities like band diagram, optical absorption and generation are calculated. Performance characteristics such as dark current and photocurrent, multiplication gain, breakdown voltage, photoresponsivity, quantum efficiency, impulse response and bandwidth etc., are presented. The modeled results of multiplication gain and bandwidth are comparable to the experimental. The results are also discussed with respect to some applicable features of Crosslight APSYS.
Back-illuminated CMOS APS with low crosstalk level
A new technological solution for backside illuminated CMOS imagers is proposed. The pixel area consists of an n-well/ substrate photo diode and a deep p-well, which contains the APS pixel circuitry as well as additional application specific circuits. This structure was analyzed using Silvaco's ATLAS device simulator. Simulation results show that this structure provides low cross-talk, high photo response and effectively shields the pixel circuitry from the photo charges generated in the substrate. The deep p-well pixel technology allows increasing the thickness of the die up to 30 micrometers, thus improving its mechanical ruggedness following the thinning process. Such deep p-well imager structure will also be integrated into the Image Transceiver Device, which combines a front side LCOS micro display with a back-illuminated imager.