This paper is intended to provide a critical review of silicide infrared staring sensors. It begins with a short tutorial on silicide cameras and internal photo-emission. This is followed by discussion of a design strategy for silicide sensors, a review of current technology status and projections of future development.
In recent years silicide Schottky-barrier focal plane technology has received great interest because it is the most promising technology for high density infrared image sensors. However, improvement in not only the detector performance but also the readout architecture is indispensable for realizing high density infrared image sensors. This paper presents the advances in silicide Schottky-barrier focal plane technology and the design considerations for high resolution infrared image sensors with video quality. A 512x512-element platinum silicide Schottky-barrier infrared image sensor with a novel readout architecture is also described.
This paper presents a practical Complementary Metal Oxide Semiconductor (CMOS) circuit design for the implementation for a multiplexer to interface a long wave length infrared Focal Plane Arrays (FPA). A Time Division Multiplexed (TDM) technique is introduced which implements Time Delay Integration (TDI).
HgCdTe photovoltaic detectors have been fabricated on Si substrates through intermediate CdTe/GaAs layers. Encapsulation of the GaAs between the CdTe and Si prevents uninten tional doping of the HgCdTe by Ga and As. Uniform epitaxial GaAs is grown on three inch diameter Si substrates. Detectors on such large area Si substrates will offer hybrid focal plane arrays whose dimensions are not limited by the difference between the coefficients of thermal expansion of the Si signal processor and the substrate for the HgCdTe detector array. The growth of HgCdTe detectors on the Si signal processors for monolithic focal plane arrays is also considered.
Problems with nonuniformity correction algorithms due to nonlinear pixel response and 1/f noise have been shown previously to cause spatial noise which can be significantly greater than temporal noise. The residual spatial noise after correction cannot be reduced with time averaging. Because of spatial noise the sensitivity of staring FPA sensors is often less than predicted on the basis of the temporal noise of the individual elements. A review is given of methods for measuring and analyzing spatial noise (after nonuniformity correction) in staring infrared focal plane arrays. Automated measurement techniques are described briefly, including necessary equipment and data reduction procedures. An example of spatial noise measurements is given using a staring InSb Charge Injection Device(CID) array.
Advances in IR Focal Plane Technology now make two dimensional detector arrays possible. It is expected that with two dimensional detector arrays the performance of IR Sensors will improve significantly. Ideally, the sensitivity improvements should scale with the square root of the number of detectors in the array. However, with larger IR arrays interdetector variations need to be compensated for. In this paper we consider quantitatively the sensitivity limitations effected by interdetector variations in quantum efficiency and spectral response, and with noise associated with calibration. Correction for the interdetector spectral variations are the most difficult and are the prime cause for sensitivity limitations. The limited sensitivity manifests itself, in scanning arrays as spectral streaking.
This paper traces the developments of the SPRITE detector from its invention in 1974 to the present day. Thermal sensitivity has been enhanced by improvements in material and the introduction of two dimensional arrays. Spatial resolution has been improved both by changes in device shape and by the introduction of anamorphic optics to reduce the effects of carrier diffusion.
This paper describes the use of band-gap engineering for designing photodiodes. Band-gap engineering is discussed in the context of low-noise avalanche photodiodes and new applications of Classes III and V materials. Recently published results are reviewed.
The physical properties of InAsSb strained-layer superlattices are reviewed. After a brief description of the band structure and superlattice growth and characterization, we present infrared absorption results and demonstrate the first device made from these materials, a p-n junction photodiode. From these studies, we find that these new materials can be designed to absorb out into the far infrared, well beyond the bandgap of any bulk III-V material. The prototype, non-optimized photodiode displayed a detectivity at 7 pm that is within one order of magnitude of the detectivity of the best HgCdTe detectors at that wavelength.
We report the first high detectivity, (D* = 1.0 X 1010 cm √Hz/W), high responsivity (Rv = 30,000 V/W), GaAs/A1),Gai_xAs multiquantum well detector, sensitive in the long wavelength infrared band (LWIR) at λ = 8.3 μm (operating at a temperature of T = 77K). Due to the mature GaAs growth and processing technologies as well as the potential for monolithic integration with high speed GaAs FETs, large focal plane arrays of these detectors should be possible.
Cincinnati Electronics' Detector and Microcircuit Devices Laboratories have built and supplied Indium Antimonide detector devices for a wide range of applications for over 25 years. During that time, dramatic improvements have been made in many areas such as uniformity, area definition and noise performance at reduced temperatures. While still a binary compound, many processing modifications are possible to optimize various performance characteristics under different conditions. In addition, various amplifier configurations for both discrete and multiplexed modes can be utilized to best fit the requirements of varying background fluxes and varying focal plane temperatures. This paper describes the present status of InSb detector technology at Cincinnati Electronics, and how a wide variety of focal plane arrays, using cooling techniques ranging from liquid helium, liquid nitrogen, J-T cryostats, mechanical coolers and passive radiative coolers, are designed and built for applications ranging from low background infrared astronomy to high background ther al imaging.
Large arrays of pyroelectric detectors, both linear and two dimensional, have the potential to satisfy many of the requirements of those IR detection and imaging tasks where low cost and minimal logistics are of paramount importance. They have however not been used in all of these applications because of apprehensions and misunderstandings concerning in particular microphony and temperature effects. This paper examines methods of pyroelectric array construction which have been developed to eliminate or minimise these effects and to offer to potential users well-characterised devices which are straight forward to operate. It concludes by presenting imagery obtained under harsh conditions.
The structure, design, and performance limitations of infrared imaging focal plane systems composed of an array of pyroelectric detectors mounted to a solid state multiplexer are discussed. Emphasis is placed on descriptions of systems of this type which are currently under development along with a simplified but accurate theory of operation. The fundamental performance limits of these solid state arrays are now well enough understood to predict that a wide variety of imaging systems with noise equivalent temperature differences of less than 0.2 ° C are feasible. When sys-tems based on these solid state focal plane arrays are commercially available, infrared imaging tech-nology will become widespread and affordable.
"Z" Technology FPA architectures provide an essential advantage over planar technologies: electronics real estate for processing individual detector signals. Originally developed for staring surveillance sensors, the "Z" architecture is now being applied to many other applications with additional ones to follow in the near future. After a description and background of "Z" technology are reviewed, examples of various military and civilian applications are discussed.