Abstract: An infrared radiation detector device has an array of detectors each of which comprises a pattern of parallel detector elements. Each detector produces a pixel signal for an image. The elements of the detector are photoconductive or photovoltaic bandgap materials and the elements are spaced apart at a dimension which is equal to or less than the wavelength of the radiation to be received. Additional layered structures above and/or below the detector elements provide impedance matching between free space radiation and the radiation impedance of the detector elements to increase the capture of radiation.

Abstract: An infrared radiation detector is disclosed which is fabricated on a dielectric substrate. The detector utilizes photosensitive segments which are included within elongate members disposed on the surface of the substrate. The elongate members comprise photosensitive detector segments which are located between and contact non-photosensitive segments and the entirety of each strip is electrically conductive. The elongate members are preferably offset from each other by less than the wavelength of the radiation and the photosensitive segments within the elongate members are also preferably spaced apart by less than the wavelength of the radiation. A reflective plane, typically an aluminum layer, is offset from the plane of the detector segments by less than the wavelength of the radiation. Incident radiation is captured by the overall detector structure which includes the reflective plane and the elongate members which include both photosensitive and non-photosensitive segments.

Abstract: An infrared radiation detector device comprises a dipole antenna mounted on a substrate and connected through blocking contacts to a bandgap detector element. The dipole antenna has a length which is approximately one half the wavelength of the incident infrared radiation. The bandgap detector element has linear dimensions which are each substantially smaller than the wavelength of the detected radiation. A group of detector devices are combined to form an array which can produce a pixel signal for an image. Unlike conventional infrared radiation detectors, the disclosed detector device is capable of producing a usable output signal without the need for cooling below ambient temperature.

Abstract: This is an integral IR detector system with at least two epitaxial HgCdTe sensors on integrated silicon or GaAs circuitry and also a method of fabricating such system. The system can comprise: a) integrated silicon or GaAs circuitry 110; b) an epitaxial lattice-match layer (e.g. ZnSe 114) on a top surface of the circuit; c) an epitaxial insulating layer (e.g. CdTe 102) on the lattice-match layer; and d) at least two epitaxial HgCdTe sensors 101,121 on the insulating layer, with the HgCdTe sensors being electrically connected to the circuitry. Preferably, the circuitry is silicon. Preferably, an IR transparent, spacer layer (e.g. CdTe 120 or CdZnTe) is on the HgCdTe sensors and an HgCdTe filter 122 is on the spacer layer. Preferably, at least one of the HgCdTe sensors and the HgCdTe filter is laterally continuously graded.

Abstract: A multi-layer Auger suppressed diode having at least two exclusion interfaces and at least two extraction interfaces. A specific embodiment has two composite contacts, each consisting of a heavily doped layer (3, 4) and a buffer layer (8, 9) of lower doped, high bandgap material sandwiched between the heavily doped layer and the active region (2) of the device.

Abstract: A sapphire substrate, a buffer layer of undoped GaN and a compound semiconductor crystal layer successively formed on the sapphire substrate together form a substrate of a light emitting diode. A first cladding layer of n-type GaN, an active layer of undoped In.sub.0.2 Ga.sub.0.8 N and a second cladding layer successively formed on the compound semiconductor crystal layer together form a device structure of the light emitting diode. On the second cladding layer, a p-type electrode is formed, and on the first cladding layer, an n-type electrode is formed. In a part of the sapphire substrate opposing the p-type electrode, a recess having a trapezoidal section is formed, so that the thickness of an upper portion of the sapphire substrate above the recess can be substantially equal to or smaller than the thickness of the compound semiconductor crystal layer.

Abstract: A structure and the fabrication method of two-color IR detector are disclosed. Disclosed two-color IR detector structure is a n-p-N structure which can be realized using only two-layer HgCdTe. The most important factor in the two-color IR detector structure is the formation of the potential barrier in the conduction band of p-N heterojunction. This potential barrier prevents photogenerated minority carriers in p-HgCdTe region from diffusing to and being collected by N-HgCdTe region (larger band gap diode). The calculated potential barrier heights under the thermal equilibrium at 77 K are 21 kT (141 meV) and 13.4 kT (89 meV) for the cases of p-Hg.sub.0.78 Cd.sub.0.22 Te/N-Hg.sub.0.69 Cd.sub.0.3l Te and p-Hg.sub.0.69 Cd.sub.0.31 Te/N-Hg.sub.0.636 Cd.sub.0.364 Te with each side carrier concentration of 5.times.10.sup.15 and 1.times.10.sub.16 cm.sup.-3, respectively.

Abstract: A method is provided for depositing a (111)-oriented heteroepitaxial II-VI alloy film on Si substrates. The (111)-oriented heteroepitaxial II-VI alloy film may comprise II-VI semiconductor and/or II-VI semimetal. As such, the method of the present invention provides a means for growing a (111)-oriented heteroepitaxial II-VI semiconductor film or a (111)-oriented heteroepitaxial II-VI semimetal film. The method of the present invention overcomes the inherent difficulties associated with forming (111)-oriented heteroepitaxial II-VI alloy films on Si(001). These difficulties include twin formation and poor crystalline quality. The novelty of the method of the present invention consists principally in choosing a Si substrate having a surface which has a specific Si crystallographic orientation. In particular, the present invention utilizes a Si surface having a crystallographic orientation near Si(111) rather than Si(001). The Si surface is vicinal Si(111).

Abstract: Self stabilizing concentration profiles are achieved in solids. More particularly, semiconductor devices are made from n- or p-type mercury cadmium telluride (MCT) of the general formula Hg.sub.x Cd.sub.1-x Te where x=0.2 to 0.5 and n- or p-type zinc mercury telluride (ZMT) of the general formula Zn.sub.x Hg.sub.1-x Te where x=0.4 to 0.6. Silver, incorporated as a doping impurity or applied as an evaporated spot electromigrated within the MCT or ZMT to create one or more p-n junctions, usually under the influence of a pulsed positive bias. The resulting concentration profiles of silver and opposing internal electric fields of the p-n junctions achieve a balancing equilibrium that preserves and maintains the stability of the concentration profiles. For a specific telluride composition, Hg.sub.0.3 Cd.sub.0.7 Te, indium is the n-type dopant of choice.

Abstract: A surface of a conductive member such as a gate electrode provided with a silicon layer is roughened. The roughened silicon layer is silicified so that its width is substantially increased, whereby phase transition of the silicide layer is simplified. Thus, the resistance of the refined silicide layer is reduced due to the simplified phase transition.

Abstract: A highly reliable solid-state image pickup device with one- or two-dimensionally arranged connecting portions, capable of avoiding corrosion of wirings resulting from chipping of the substrates and eliminating image defect, is achieved by arranging plural substrates, each bearing a plurality of image taking elements, in a planar manner on a supporting substrate and filling the connecting portions of thus arranged substrates with an organic or inorganic material, of which content in chlorine or in each of sodium and potassium does not exceed 200 ppm.

Abstract: This invention relates to mounting integrated circuits (IC) to multi-chip modules (MCM) or substrates. More specifically, it provides a method of mounting a semiconductor die such as a thin slice of Mercury Cadmium Telluride (MCT) to a silicon semiconductor substrate, a read-out integrated circuit (ROIC), using a thermoplastic to reduce stress on the MCT caused by mismatched Coefficients of Thermal Expansion (CTE). This process provides for an array of infrared photodetectors on a material such as MCT to be mounted to a read-out integrated circuit (ROIC) using the Vertical Integrated Photodiode (VIP) approach to FPAs, while allowing double sided interdiffusion of CdTe for surface passivation to reduce dark currents and improve performance, without the problems associated with mismatched coefficients of thermal expansion during high temperature processes.

Abstract: An array (41) is comprised of a plurality of radiation detectors (10, 10') each of which includes a first photoresponsive diode (D1) having an anode and a cathode that is coupled to an anode of a second photoresponsive diode (D2). The first photoresponsive diode responds to electromagnetic radiation within a first band of wavelengths and the second photoresponsive diode responds to electromagnetic radiation within a second band of wavelengths. Each radiation detector further includes a first electrical contact (26) that is conductively coupled to the anode of the first photoresponsive diode; a second electrical contact (28) that is conductively coupled to the cathode of the first photoresponsive diode and to the anode of the second photoresponsive diode; and a third electrical contact (30) that is conductively coupled to a cathode of each second photoresponsive diode of the array. The electrical contacts are coupled during operation to respective bias potentials.

Abstract: A heterostructure thermionic cooler and a method for making thermionic coolers, employing a barrier layer of varying conduction bandedge for n-type material, or varying valence bandedge for p-type material, that is placed between two layers of material. The barrier layer has a high enough barrier for the cold side to only allow "hot" electrons, or electrons of high enough energy, across the barrier. The barrier layer is constructed to have an internal electric field such that the electrons that make it over the initial barrier are assisted in travel to the anode. Once electrons drop to the energy level of the anode, they lose energy to the lattice, thus heating the lattice at the anode. The barrier height of the barrier layer is high enough to prevent the electrons from traveling in the reverse direction.

Abstract: A semiconductor device having: a support substrate having an upper surface; a HgTe layer formed on the support substrate; and a HgCdTe layer directly formed on the HgTe layer. A semiconductor device of another type having: a support substrate having an exposed upper surface tilted from the (100) plane of a single crystal with a diamond structure by a certain angle, along a direction offset by an angle larger than 0.degree. and smaller than 45.degree. from the ?011! direction in the (100) plane; a group III-V compound semiconductor layer formed on the support substrate; and a group II-VI compound semiconductor layer formed on the group III-V compound semiconductor layer.

Abstract: An array 1 of photodiodes 2 is comprised of a Group II-VI material, such as HgCdTe, which may be selectively doped to form a plurality of diode junctions. Array 1 is comprised of a plurality of photodiodes 2 which are disposed in a regular, two dimensional array. Incident IR radiation, which may be long wavelength, medium wavelength or short wavelength (LWIR, MWIR or SWIR) radiation, is incident upon a surface of the array 1. The array 1 comprises a radiation absorbing base layer 3 of Hg.sub.1-x Cd.sub.x Te semiconducting material, the value of x determining the responsivity of the array to either LWIR, MWIR or SWIR. Each of the photodiodes 2 is defined by a mesa structure, or cap layer 3; or the array 1 of photodiodes 2 may be a planar structure. Each of the photodiodes 2 is provided with an area of contact metallization 4 upon a top surface thereof, the metallization serving to electrically couple an underlying photodiode to a readout device.

Abstract: A Group II-VI IR photodiode 10 has a passivation layer 16 overlying at least exposed surfaces of the p-n diode junction 15, the passivation layer being a compositionally graded layer comprised of Group II atoms diffused into a surface of the p-n diode junction. The passivation layer has a wider energy bandgap than the underlying diode material thereby repelling both holes and electrons away from the surface of the diode and resulting in improved diode operating characteristics. A cation substitution method of the invention includes the steps of preparing a surface to be passivated, such as by depleting an upper surface region of Group II atoms; depositing a layer comprised of a Group II material over the depleted surface region; and annealing the deposited layer and underlying Group II-VI material such that atoms of the deposited Group II layer diffuse into the underlying depleted surface region and fill cation vacancy sites within the depleted surface region.

Abstract: In one embodiment, a semiconductor structure is disclosed. The structure includes both a silicon and a cadmium telluride layer. Each may have a (100) lattice orientation. A plurality of buffer layers are disposed between the silicon layer and the cadmium telluride layer. Each of these buffer layers has a lattice constant which is greater than the lattice constant of the layer below it and less than the lattice constant of the layer above it. As examples, these buffer layers may comprise zinc sulfide, zinc selenide, zinc telluride or zinc tellurium selenide.

Abstract: An imaging device (10) has a plurality of unit cells that contribute to forming an image of a scene. The imaging device includes a layer of semiconductor material (16), for example silicon, that has low noise photogate charge-mode readout circuitry (20, 21, 26, 28) (e.g., CCD or CMOS readout circuitry and structures) that is disposed upon a first surface (18) of the layer. A second, opposing surface of the layer is a radiation admitting surface of the layer. The layer has a bandgap selected for absorbing electromagnetic radiation having wavelengths shorter than about one micrometer and for generating charge carriers from the absorbed radiation. The generated charge carriers are collected by the photogate charge-mode readout circuitry. A thermal sensing element (22) is disposed above and is thermally isolated from the first surface of the layer. The thermal sensing element may be, by example, one of a bolometer element, a pyroelectric element, or a thermopile element.

Abstract: A detector to be used for detecting photons from the visible to far infrared spectrum is described. The detector uses unique photocathodes called Advanced Semiconductor Emitter Technology (ASET) as its critical element for converting the detected photons to electrons which are emitted into a vacuum. The electron is multiplied by accelerations and collisions creating a signal larger than the sensor noise and thus allowing the photon to be detected. ASET is/composed of distinct detector and emitter technologies.

Abstract: Described is a semiconductor photo detector comprising, between two electrodes, at least one of said electrodes being a transparent electrode, an optical absorption layer which is composed of a non-single crystalline material, absorbs light and generates photo carriers and a carrier multiplication layer which is composed of a non-single crystalline material and multiplies the photo carriers generated by the optical absorption layer. The carrier multiplication layer is formed of a multilayer film obtained by stacking films each having plural layers which are composed of non-single crystalline Zn.sub.x Cd.sub.1-x M (0.ltoreq.x.ltoreq.1, M represents one selected from the group consisting of S, Se and Te) and are different in a composition ratio in accordance with a change in the value of x in said Zn.sub.x Cd.sub.1-x M, whereby a band discontinuity .DELTA.Ec of the conduction band can be made larger, an ionization rate of electrons can be heightened and the place where ionization occurs can be specified.

Abstract: An epitaxial structure and method of manufacture for a infrared detector device with low dislocation density, especially for high performance large area focal plane arrays. Preferably, the epitaxial structure includes a buffer layer comprising a Hg-based II-VI material and an overlayer comprising a detector comprising a Hg-based II-VI material. The buffer layer is transparent at the operating frequencies of the detector.

Abstract: A substantial portion of the material at the pn junction (27) of the photodiode (37, 41) having an implanted region extending to a surface thereof is selectively removed (39), leaving a very small junction region (35, 43) with the remainder of the p-type (23) and n-type (25) material of each photodiode being spaced apart or electrically isolated at what was originally the junction. In the ion implanted n-type on p-type approach, the majority of the signal is created in the implanted n-type region while the majority of the noise is generated in the p-type region. By selectively removing p-type material, n-type material or both from the pn junction of the diode or otherwise electrically isolating most of the p-type and n-type regions from each other at the pn junction and thereby minimizing the pn junction area, noise is greatly reduced without affecting the signal response of the photodiode.

Abstract: A photoresponsive device (10) includes a body comprised of semiconductor material comprised of elements selected from Group IIB-VIA; and at least one electrically conductive contact pad (20) formed over a surface of the semiconductor material. The at least one electrically conductive contact pad is comprised of metal nitride, such as MoN, and serves as a diffusion barrier between an Indium bump (22a, 22b) and the underlying semiconductor material. A passivation layer (18), such as a layer of wider bandgap CdTe, can be formed to overlie the surface of said semiconductor material. A p-n junction is contained within a mesa structure (10a) that comprises a portion of an n-type base layer (14) and a p-type cap layer (16). A first contact pad is disposed over the cap layer and a second contact pad is disposed over the base layer.

Abstract: A semiconductor photoelectric converting device and an imaging device using such semiconductor photoelectric converting devices are provided according to the present invention, the semiconductor photoelectric converting device including an electric charge transfer area provided in a surface portion of a semiconductor substrate and a light-receiving area formed of a piezoelectric material, electrically connected to the electric charge transfer area and provided in contact with the semiconductor substrate, in which electric charges generated by a piezoelectric effect produced by a strain resulting from heat evolved upon the falling of light onto the light-receiving area are conducted to the charge transfer area.

Abstract: In a method for fabricating an infrared detector, initially, a CdHgTe layer of a first conductivity type is produced on a front surface of a semiconductor substrate, a plurality of spaced apart CdHgTe regions of a second conductivity type, opposite the first conductivity type, are produced at the surface of the first conductivity type CdHgTe layer, and part of the surface of the first conductivity type CdHgTe layer between the second conductivity type CdHgTe regions is selectively irradiated with a charged particle beam to evaporate Hg atoms from that part, whereby a CdHgTe separation region of the first conductivity type and having a Cd composition larger than that of the first conductivity type CdHgTe layer is produced penetrating through the first conductivity type CdHgTe layer and surrounding each of the second conductivity type CdHgTe regions. Therefore, a highly-integrated high-resolution infrared detector with no crosstalk between pixels is achieved.

Abstract: A substantial portion of the material at the pn junction (27) of the photodiode (37, 41) having an implanted region extending to a surface thereof is selectively removed (39), leaving a very small junction region (35, 43) with the remainder of the p-type (23) and n-type (25) material of each photodiode being spaced apart or electrically isolated at what was originally the junction. In the ion implanted n-type on p-type approach, the majority of the signal is created in the implanted n-type region while the majority of the noise is generated in the p-type region. By selectively removing p-type material, n-type material or both from the pn junction of the diode or otherwise electrically isolating most of the p-type and n-type regions from each other at the pn junction and thereby minimizing the pn junction area, noise is greatly reduced without affecting the signal response of the photodiode.

Abstract: A photoconductive isotype heterojunction impedance-matched infrared detector has blocking contacts which are positioned on the bottom side of the detector. The blocking contacts prevent transfer of minority carriers from the active region of the detector, thereby extending the lifetime of these carriers. The detector is formed by first fabricating an active layer followed by an isotype blocking layer on a growth substrate. These layers are etched and appropriate passivation layers and contacts are applied. A mechanical supporting substrate is applied to the detector and the growth substrate is removed. Etch stop holes are formed which extend into the active layer of the detector. A precision thickness of the active layer required in an impedance-matched detector design is produced by thinning the active layer in an etching process until the surface of the active layer reaches the etch stop hole.

Abstract: The present invention provides an Si base semiconductor monocrystal substrate which includes an Si(11n) substrate where n=1.5-2.5. An intermediate layer is formed on the Si(11n) substrate. The intermediate layer is made of a material selected from the group consisting of ZnTe and Zn-rich CdZnTe, The intermediate layer has a thickness in the range of 50-200 angstroms. The intermediate layer is oriented in a (11n')B plane. An upper layer is formed on the intermediate layer. The upper layer is made of a material selected from the group consisting of CdTe and Cd-rich CdZnTe. The upper layer is oriented in a (11n")B plane. The indexes n' and n" satisfy the following equations. ##EQU1## where y is the lattice mismatch between the Si substrate and the intermediate layer. ##EQU2## where y' is the lattice mismatch between the Si substrate and the upper layer.

Abstract: An electromagnetic radiation transducer is provided having a p-type ZnSe layer and an n-type layer. The p-type ZnSe layer has a net donor to net acceptor ratio (N.sub.D /N.sub.A) of less than or equal to about 0.8. The net acceptor concentration is greater than about 5.times.10.sup.15 cm .sup.-3 and the resistivity is less than 15 .OMEGA.-cm. The p-type ZnSe layer is deposited by doping the ZnSe during fabrication with a neutral free-radical source.

Abstract: A photovoltaic diode unit cell (10) includes a first layer (14) having a first type of electrical conductivity and a second layer (16) of Group II-VI material having a second type of electrical conductivity that differs from the first type. The first layer and the second layer are coupled together so as to form a photovoltaic junction (15) therebetween. The photovoltaic junction is coupled via electrical interconnects (18, 20, 22) to a readout 24 and collects first charge carriers resulting from an absorption of IR radiation within the layer 14. The junction also collects second charge carriers resulting from the absorption of visible light in a region of highly graded crystal potential formed, in a Liquid Phase Epitaxy (LPE)-grown embodiment of this invention, at an interface of a substrate and the first layer. The substrate is subsequently removed, preferably by a mechanical operation followed by a wet chemical etch, to expose the region of highly graded crystal potential.

Abstract: A radiation detector (1) unit cell (10) includes an n-p+ LWIR photodiode that is vertically integrated with a p+-n MWIR photodiode in a n-p+-n structure. Electrical contact is made separately to each of these layers in order to simultaneously detect both the LWIR and MWIR bands. The electrical contact is made via indium bump interconnections (23, 25, 27) enabling the unit cell to be subsequently hybridized with a topside mounted electronic readout integrated circuit (30). The n-p+-n structure in a given pixel of an array of radiation detector pixels is electrically isolated from all neighboring pixels by a trench (28) that is etched into an underlying substrate (12). To compensate for a reduction in the optically sensitive area due to the placement of the electrical contacts and the presence of the pixel isolation trench, a microlens (34) may be provided within, upon, or adjacent to the backside, radiation receiving surface of the substrate in registration with the unit cell.

Abstract: An improved x-ray detector in the form of a p-i-n CdTe homojunction device is disclosed. The intrinsic ("i") layer is of high resistivity CdTe, while the n- and p-doped CdTe layers are epitaxially grown in a photo-assisted process in a molecular beam epitaxial apparatus. The n-dopant is conveniently indium, with an indium metal contact. The "i" layer is optionally epitaxially grown in a photo-assisted process. The p-dopant is preferably arsenic. A PAMBE formed mercury telluride contact layer enhances the ohmic contact to the p-layer, and a gold contact is provided to the contact layer. The use of the PAMBE technique facilitates high quality crystal growth and activation of the dopants. The resulting CdTe p-i-n homojunction device has a wide band gap (1.45 eV) essential to room temperature operation.

Abstract: A compositionally graded HgCdTe radiation detector (10) is constructed to have a high purity "denuded zone" (Region 2) that is formed adjacent to a radiation absorbing region (Region 1). The compositional grading results in an internally generated electric field that is orthogonally disposed with respect to an externally generated electric field applied between contacts (16, 18). The internally generated electric field has the effect of injecting photogenerated minority charge carriers into the denuded zone, thereby reducing recombination with photogenerated majority charge carriers and increasing carrier lifetime. The detector further includes a wider bandgap surface passivation region (Region 3) that functions to trap, or "getter", impurities from the denuded zone and also to reduce surface recombination effects.

Abstract: A dual-band HgCdTe radiation detector (10) includes a four layer n-p.sup.+ -p-n.sup.+ structure, grown by LPE, upon a substrate (12). The four layers are, from a bottom layer next to the substrate to the surface: (a) a MWIR radiation responsive n-type absorbing layer (14); (b) a p.sup.+ cap layer (16); (c) a LWIR radiation responsive p-type layer (18); and (d) an n+ top layer (20). The n.sup.+ top layer has a compositional profile that is similar to the p-type cap layer. Operation of this structure involves biasing the top layer positive with respect to the bottom layer, which results in the collection of LWIR-generated electrons in the p-type layer. Biasing the top layer negative with respect to the bottom layer results in MWIR-generated holes being collected by the bottom n-p+ junction.

Abstract: A first type of superconductive photoelectric device is provided by a superconductive thin film located between two electrodes. The superconductive thin film is one which has a photo-conductive effect and converts from a normally conducting state to a superconductive state in response to light irradiation. The superconductive thin film is preferably formed of a compound semiconductor of Pb chalcogenide added with Pb and/or In added beyond the stoicheometry of the compound semiconductor, such as Pb.sub.1-x Sn.sub.x Te+In, so as to generate precipitations of Pb. A second type of superconductive photoelectric device is provided by a photo-conductive material formed of Pb.sub.1-x Sb.sub.x Te filled in a gap between two superconductive electrodes, where the gap width is shorter than 500 times of a coherence length.

Abstract: An integrated radiation detector (10) includes a substrate (12) having a first region (14) comprised of Group III-V semiconductor material, such as GaAs, formed over a first surface, and a second region (26) comprised of Group II-VI semiconductor material, for example HgCdTe, formed over a second, opposite surface. The second region has a bandgap selected for absorbing radiation within a first range of wavelengths, such as IR radiation within the range of 12 micrometers to three micrometers. A first detector includes an antenna structure (20) coupled to a Schottky contact (22) for detecting electromagnetic radiation having wavelengths within a second range of wavelengths, such as wavelengths corresponding to frequencies within a range of approximately 30 GHz to approximately 1000 GHz. A second detector includes a photoconductive or photovoltaic infrared detector for collecting charge carriers generated by the absorption of the IR radiation.

Abstract: Only the areas of the CdTe/HgCdTe interface of a FPA detector circuit which is coupled by an epoxy to a silicon-based integrated circuit that require interdiffusing are heated to a sufficiently high temperature or have photons of light impinging thereon for a sufficient time to cause interdiffusion of the two layers by the travel of tellurium into the HgCdTe and the travel of mercury into the CdTe. The vast majority of the wafer is masked with an aluminum thin film to greatly reduce heat gain or photon transmission. An advantage of the process in accordance with the present invention is that only a very small fraction of the HgCdTe/epoxy/silicon-based integrated circuit wafer receives incoming energy during interdiffusion whereby problems caused by the differences in coefficient of thermal expansion between silicon and HgCdTe at the epoxy interface are minimized.

Abstract: A radiation detector includes a photovoltaic diode mesa structure (16) having of a plurality of sub-mesa structures (16a, 16b). Each of said sub-mesa structures includes a first layer (14a) of semiconductor material having a first type of electrical conductivity and a second layer (14b) having a second type of electrical conductivity such that a p-n junction is formed between the first and the second layers. Metalization (24) is disposed within a trench (30a) that runs between the sub-mesas and includes a tab portion (24a) that extends upwardly over a sidewall of each of said sub-mesa structures so as to electrically contact the second layer contained within each. As a result, each of said sub-mesa structures are electrically connected in parallel.

Abstract: Self stabilizing concentration profiles are achieved in solids. More particularly, semiconductor devices are made from n- or p-type mercury cadmium telluride (MCT) of the general formula Hg.sub.x Cd.sub.1-x Te and especially using Hg.sub.0.3 Cd.sub.0.7 Te. Silver, incorporated as a doping impurity or applied as an evaporated spot electromigrates within the MCT to create one or more p-n junctions, usually under the influence of a pulsed positive bias. The resulting concentration profiles of silver and opposing internal electric fields of the p-n junctions achieve a balancing equilibrium that preserves and maintains the stability of the concentration profiles. For the specific telluride composition, indium is the n-type dopant of choice.

Abstract: An infrared imaging device includes a first conductivity type first semiconductor layer having a small energy band gap, a first conductivity type second semiconductor layer have a larger energy band gap and disposed on the first semiconductor layer, a light receiving region of the second conductivity type in the second semiconductor layer and extending into the first semiconductor layer, a second conductivity type region in the second semiconductor layer spaced from the light receiving region, an insulating layer on the second semiconductor layer, and an MIS electrode on the insulating layer between the light receiving region and the second conductivity type region. Recombination of signal charges produced by incident light in the light receiving region and leakage current at the surface of the second semiconductor layer at the light receiving region are reduced. In addition, the numerical aperture of the light receiving region is increased.

Abstract: A photoresponsive device wherein the device includes semiconductor material, such as a cap region (14a), comprised of elements selected from Group IIB-VIA. A molybdenum contact pad (16) is formed upon a surface of the cap region, and a molybdenum ground contact pad is formed on a surface of a base region (12). A wide bandgap semiconductor passivation layer (20) overlies the surface of the cap region and also partially overlies the molybdenum contact pad. A dielectric layer (22) overlies the passivation layer, and an indium bump (24) is formed upon the molybdenum contact pad. The dielectric layer is in intimate contact with side surfaces of the indium bump such that no portion of the molybdenum contact pad can be physically contacted from a top surface of the dielectric layer. This method eliminates the possibility of unwanted chemical reactions occurring between the In and the underlying contact pad metal.

Abstract: A light emitting semiconductor heterojunction includes a first layer of n-type semiconducting material comprising a Group II-VI material, and a second layer of p-type semiconducting diamond on the first layer. Preferably the Group II-VI material includes a Group II material selected from the group consisting of zinc and cadmium, and the Group VI material is selected from the group consisting of sulfur and selenium. The light emitting heterojunction will produce light having a wavelength in the range of about 440-550 nanometers, depending on the composition and the temperature of operation. One embodiment of the device is a surface emitting device and includes a contact layer on the diamond layer having a predetermined shape, such as a ring, overlying only a portion of the diamond layer for permitting surface emission of light from diamond layer.

Abstract: A light emission diode comprises a semiconductor substrate and a pn junction structure including an n-type ZnS compound semiconductor layer and a p-type ZnS compound semiconductor layer, Al being present in at least one of the semiconductor layers. By this, the diode is able to emit blue light at a high luminous intensity.

Abstract: Disclosed is a method of fabricating a two-color radiation detector, and two-color photodetectors fabricated by the method. A structure is grown upon a substrate (10) to provide, in sequence, a LPE grown LWIR n-type layer (12), a MWIR p+ type common contact layer (14), and a MWIR n-type layer (16). Following growth of the MWIR n-type layer, a layer of passivation (18) is applied, and the substrate is removed to so as to enable further processing of the structure into an array (1) of two-color photodetectors. The three layer structure is bonded, prior to further processing, to a supporting substrate (22) with an adhesive bond made to the passivation layer. The supporting substrate is comprised of IR transparent material such as Group IIB-VIA semiconductor material, Group IIIA-VA semiconductor material, Group IVA semiconductor material, sapphire, and combinations thereof.

Abstract: A HgCdTe S-I-S (semiconductor-insulator-semiconductor) two color infrared detector wherein the semiconductor regions are HgCdTe with different compositions for the desired spectral regions. The device is operated as a simple integrating MIS device with respect to one semiconductor. The structure can be grown by current MBE techniques and does not require any significant additional steps with regard to fabrication.

Abstract: A radiation detector (1) includes a multi-layered substrate (2,10) having a first major surface, which is a radiation receiving surface, and a second major surface disposed opposite to the first major surface. A first detector is formed adjacent to the first major surface, the first detector being responsive to a wavelength or wavelengths of electromagnetic radiation in the range of approximately 0.3 micrometers (near-UV) to approximately 1.2 micrometers (near-IR). A second detector is formed adjacent to the second major surface of the multi-layered substrate, the second detector being responsive to a wavelength or wavelengths of electromagnetic radiation in the range of approximately one micrometer to approximately twenty micrometers (SWIR to VLWIR). In a presently preferred embodiment the second detector is simultaneously responsive to IR radiation within two distinct spectral bands.

Abstract: Spectral shift between different wavelength spectra by restricted narrow bandgap absorption of incident radiation at one location on a semiconductor body, under electrical bias causing release of radiation at another emission location as a result of radiative electron-hole recombination. The semiconductor body is a graded bandgap establishing composition of two selected compounds alloyed to a variable, position-dependent degree between the respective radiation and emission locations at which the respective narrow and wide bandgap properties of the compounds prevail.

Abstract: A hybrid infrared focal plane array detector employs a detector layer and transparent substrate bonded to a thin semiconductor readout integrated circuit and thicker readout circuit substrate. The readout circuit is rigidly bonded to the readout substrate to form a composite structure having a thermal coefficient of expansion substantially matching that of the detector portion. The hybrid device may be cooled from room temperature to cryogenic operation temperatures without thermal mismatch structural problems.

Abstract: A low doped semiconductive layer is formed on a semiconductor substrate of a highly doped first conductivity type, and a first region of a highly doped second conductivity type is selectively formed at a portion of the semiconductive layer. In a top-incidence type photo-sensing device having a pn junction area of the above structure as a photo-sensing region, the first region is surrounded by a second region of the second conductivity type formed at a portion of the semiconductor layer. The second region has the same or a larger depth as that of the first region. Thus, even if light is directed to the outside of the photo-sensing region, extra charges generated therein are absorbed by the second region and the flow of extra charges into the photo-sensing region is prevented.