United States of America As Represented by the Secretary of the Air Force

Paul W Pellegrini

Charlotte E Ludington

Melanie M Weeks

Freeman D Shepherd

Steven DiSalvo

Aleksandar Golubovic

Michael J Noyola

Luigi Spagnuolo

Jorge R Jimenez

Mark Gill

A method, apparatus and program product are provided for simplifying electro-optical imaging data. Spectral/temporal data is received. The spectral/temporal data is formulated into a vector/matrix. Feature extraction analysis is performed. At least two largest principal components are determined from the feature extraction analysis. A cluster diagram is created from the at least two largest principal components. A distance metric is evaluated from the cluster diagram. And, a largest metric is selected based on the distance metric.

Method and apparatus for simplifying electro-optical imaging systems

PtSi/Si Schottky diode infrared detectors are currently being used in large-area focal plane arrays for imaging in the 3-5 micron atmospheric transmission window. Their photoresponse cuts off at about 6 microns, beyond which they cannot detect infrared ratiation. Because of the nature of Schottky diodes, this cut-off wavelength cannot be adjusted during operation, but is relatively fixed, varying only in proportion of the fourth root of an externally applied bias. This disclosure describes a Schottky diode infrared detector with a voltage-tunable cut-off wavelength. The tunability is obtained by modification of the Schottky diode band diagram by insertion of a SiGe layer, with the appropriate parameters, between the silicide and the Si substrate, making the detector a silicide/SiGe/Si Schottky diode detector. The SiGe/Si interface has a valence band offset that can be used to engineer the shape, or depth profile, of the Schottky barrier. The energy offset can be gradual or abrupt, depending on the grading of the Ge concentration in the SiGe layer. When the offset is abrupt, it can be thought of as an additional, higher energy barrier to photoemitted carriers if the SiGe layer is thin enough. Because this offset, gradual or abrupt, is designed to be deeper in the semiconductor than the normal Schottky barrier maximum, it is easily modified by an external applied voltage. The sensitivity and the range of tunability are defined by the SiGe thickness and Ge concentration, respectively.

Voltage tunable schottky diode photoemissive infrared detector

Platinum Silicide (PtSi) layers formed on silicon substrates are well known for their ability to image in the infrared portion of the electromagnetic spectrum out to 5.75 micrometers. The detectors are formed on p-type silicon substrates of &lt;100&gt; orientation. This is the preferred crystal structure for silicon when used for fabrication of Very Large Scale Integration (VLSI). The cooling required for these devices is 77.degree. K., which is needed to reduce thermal currents in the diodes to be significantly below the infrared generated signal. Detector array operation at these temperatures does not allow for operation in space for extended missions because a closed cycle mechanical cooler must be used. We have developed a new PtSi detector which must be fabricated on p-type silicon having a &lt;111&gt; crystal orientation. The detectors have been measured for their cutoff wavelength and barrier height is 0.310 eV which translates to a cutoff wavelength of 4.0 micrometers. The cooling required to operate these new devices is 110.degree. K. This means that they can be used in space applications where passive cooling is required.

Platinum silicide infrared diode

A Schottky barrier diode formed of iridium-silicon material having a frequency response encompassing the 3.0 to 5.0 micrometer infrared band. The bandwidth, uniformity of response and silicon base material of such diodes renders them ideally suited for use in large scale focal plane arrays associated with infrared cameras.

Schottky barrier infrared detector and process

A two dimensional focal plane array of Schottky photodiodes on a silicon substrate for infrared imaging. The array is designed for mating with multiplexing circuitry and has a self-guarding feature wherein adjacent Schottky electrodes act as guard electrodes. This feature allows a substantial increase of the focal plane area coverage ratio.

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Bedford, MA, United States of America

Paul W Pellegrini