University of Pittsburgh

Other

Microtronics Associates, Inc.

Darryl D Coon

Gustav Edward Derkits, Jr

Hui C Liu

Jayanth R Banavar

Runkiri P Karunasiri

A G Perera

John P Elliott

Ralph E Sherriff

Robert P Devaty

Far infrared light is detected using semiconductor devices having at least two doped layers with adjacent doped layers separated by undoped layers. The technique includes doping to levels which establish work functions at interfacial barriers between the doped and undoped layers approximately equal to the photon energy of far infrared light of the longest wavelength to be detected. The devices are forward biased, cooled to a temperature at which thermal excitation of carriers in the doped layers is less than the work function, and exposed to far infrared light of a band width including the selected longest wavelength. Photo current produced by excitation of carriers over the interfacial barriers is then measured. The method can be applied to existing p-i-n diodes and superlattice structures as well as devices fabricated to respond to specific far infrared wavelength bands.

Method of operating p-i-n diodes and superlattice devices as far

Multi-element high energy particle detector modules comprise a planar heavy metal carrier of tungsten alloy with planar detector units uniformly distributed over one planar surface. The detector units are secured to the heavy metal carrier by electrically conductive adhesive so that the carrier serves as a common ground. The other surface of each planar detector unit is electrically connected to a feedthrough electrical terminal extending through the carrier for front or rear readout. The feedthrough electrical terminals comprise sockets at one face of the carrier and mating pins porjecting from the other face, so that any number of modules may be plugged together to create a stack of modules of any desired number of radiation lengths. The detector units each comprise four, preferably rectangular, p-i-n diode chips arranged around the associated feedthrough terminal to form a square detector unit providing at least 90% detector element coverage of the carrier. Integral spacers projecting from the carriers extend at least partially along the boundaries between detector units to space the p-i-n diode chips from adjacent carriers in a stack. The spacers along the perimeters of the modules are one-half the width of the interior spacers so that when stacks of modules are arranged side by side to form a large array of any size or shape, distribution of the detector units is uniform over the entire array.

Modular multi-element high energy particle detector

A fast, real time method and apparatus for long wavelength infrared photodetection employs a quantum well from which stored electrons are ejected by photoemission and replaced by electrons which tunnel through a barrier bounding one side of the quantum well. The photodetector comprises a semiconductor device having a quantum well layer separated from an emitter layer on one side by a first barrier layer and from a collector layer on the other side by a second barrier layer. The first barrier is higher than the second which in turn is higher than the Fermi level in the quantum well layer. Photons excite electrons in the quantum well to an excited state from which they flow over the second barrier to the collector layer. Electrons tunnel from the emitter through the first barrier to the quantum well at the rate at which they are depleted by photoemission so that the detector is suitable for use with high pulse rate digital communication signals.

Intraband quantum well photodetector and associated method

The present invention relates to a novel semiconductor heterostructure device characterized by improved coupling of tunnelling current to an electromagnetic field in the region between doped conductive layers of the device comprising a first conductive contact layer comprising a semiconductor including a dopant material, a barrier layer in juxtaposition to the first conductive contact layer comprising a semiconductor of a different material than that of the first layer to control the tunnelling current, a non-barrier layer in juxtaposition to the barrier layer comprising an undoped, semiconductor material to provide improved coupling to the electromagnetic field, a second conductive contact layer comprising a semiconductor including a dopant material, and means for applying a bias voltage potential across the device to generate photon emissions. The invention further relates to a method of producing a far infrared and/or microwave radiation source from radiative tunnelling transitions in a semiconductor device having at least one barrier layer and a plurality of doped conductive contact layers comprising the steps of passing an intraband tunnelling current through the device so as to provide that the photon creation rate of said device is larger than the ohmic damping loss rate, and directing the emitted photons from said device so that the device functions as an electromagnetic radiation emitter which provides increased coupling of said tunnelling current to an electromagnetic field located in the region between the doped conductive layers.

Semiconductor device and method for producing a far infrared and/or

An apparatus and method for infrared imaging is disclosed in which a pattern of infrared radiation is detected and stored in uniformly distributed localized states in a semiconductor. Photoemission of charge carriers from the localized states occurs only at locations where infrared photons interact with the carriers. When desired, a uniform electric field applied to the semiconductor allows for coherent transport of a pattern of remaining carriers in a direction substantially perpendicular to an outer surface to which the image is transported. A portion of the transported pattern of charge may be emitted from the outer surface of the semiconductor and utilized to produce an optical or electrical pattern corresponding to the incident infrared pattern.

Apparatus and method for infrared imaging

An infrared detector and method of detection based on depletion of charge stored in localized states is disclosed. The detector and method involve the determination of the depletion of charge stored in localized states at low temperatures caused by electric field-assisted photoemission of charge carriers from the localized states. The depletion of stored charge is indicative of the integrated incident flux of infrared radiation. The depletion of stored charge can be sensed by quantum mechanical field ionization, field detachment or otherwise.

Apparatus and method for detection of infrared radiation

A semiconductor memory device exhibiting non-volatile storage characteristics is disclosed. The device comprises a storage element, maintained in a prescribed range of temperatures, which exhibits an effect of charge storage and release of the stored charge upon application of a suitable bias voltage. Information is stored by exposure to light or by applying a suitable bias voltage to put the device into one of a multiplicity of long-lived states. In the case of exposure to light the state of the device is indicative of the integrated photon flux. Information can be stored or read out in times as short as 1 nanosecond or less and will remain stored for as long as 10.sup.5 seconds or longer without any sustaining voltage. A plurality of the memory devices can be interconnected in an array and can be used as a memory storage bank.

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Pittsburgh, PA, United States of America

Darryl D Coon