Abstract: An avalanche photodiode having an absorption zone, a multiplication zone, and a transition zone disposed between the absorption zone and the multiplication zone, the transition zone being doped and being constituted at least in part by a material of composition that is graded such that the energy bands of the structure are substantially continuous when it is biased, wherein said doping is distributed non-uniformly in said graded composition zone so as to compensate, at least in part, the reverse electric field due to the composition grading of the material in the transition zone.

Abstract: A radiation-damage resistant radiation detector is formed on a substrate formed of a material doped with a first conductivity type dopant. The detector includes at least one first electrode formed of first conductivity type dopant, and at least one second electrode that is spaced-apart from the first electrode and formed of a second conductivity type dopant. Each first and second electrode penetrates into the substrate from a substrate surface, and one or more electrodes may penetrate entirely through the substrate, that is traversing from one surface to the other surface. Particulate and/or electromagnetic radiation penetrating at least a surface of the substrate releases electrons and holes in substrate regions. Because the electrodes may be formed entirely through the substrate thickness, the released charges will be a relatively small distance from at least a portion of such an electrode, e.g., a distance less than the substrate thickness.

Abstract: A semiconductor device that enables to prevent the electron transport property of a semiconductor active layer from degrading even if a semiconductor compositionally-graded buffer layer is used. This device contains a semiconductor substrate, a semiconductor active layer lattice-mismatched with the substrate, and a semiconductor compositionally-graded buffer layer formed between the substrate and the active layer. The compositionally-graded buffer layer has a semiconductor superlattice structure including first semiconductor sublayers and second semiconductor sublayers that are alternately stacked in a direction perpendicular to the substrate. Each of the first sublayers is made of a first semiconductor material. Each of the second sublayers is made of a second semiconductor material different in composition from the first semiconductor material. The lattice constant of the first and second sublayers decreases or increases stepwise from a side near the substrate and the other side near the active layer.

Abstract: A photoelectric conversion device including: a photoelectric conversion portion having a light absorbing layer disposed between charge injection inhibition layers and having a predetermined forbidden band width Eg.sub.1, and a carrier multiplication portion including a single or a plurality of inclined band gap layers, the inclined band gap layer including a minimum forbidden band width Eg.sub.2 and a maximum forbidden band width Eg.sub.3 which are disposed to be in contact with each other to form a hetero junction and having, at the two ends thereof, forbidden band widths Eg.sub.4 which holds a relationship Eg.sub.2 <Eg.sub.4 <Eg.sub.3 in such a manner that the forbidden band width is continuously changed from the two forbidden band widths Eg.sub.2 and Eg.sub.3 to the forbidden band width Eg.sub.4, and the energy step in a conductive band of the hetero junction portion is larger than the energy step in a valence electron band, wherein at least the minimum forbidden band width Eg.sub.

Abstract: In the structure of the device of the invention, a supper-lattice buffer layer is formed between the undoped layer and doped layers. This super-lattice buffer layer serves as a carrier-piling up layer in place of the undoped layer in the conventional device. Thus, the amounts of the piled-up carriers in the undoped layer can be greatly reduced and hence no band filling effect occurs in the undoped layer. Consequently, an optical device having a flat frequency characteristic can be produced without losing its modulating characteristic.

Abstract: A photoelectric emission surface which is excellent in stability and reproducibility of photoelectric conversion characteristics and has a structure capable of obtaining a high photosensitivity is provided. A predetermined voltage is applied between an upper surface electrode and a lower surface electrode by a battery. Upon application of this voltage, a p-n junction formed between a contact layer and an electron emission layer is reversely biased. A depletion layer extends from the p-n junction into the photoelectric emission surface, and an electric field is formed in the electron emission layer and a light absorbing layer in a direction for accelerating photoelectrons. When incident light is absorbed in the light absorbing layer to excite photoelectrons, the photoelectrons are accelerated by the electric field toward the emission surface.

Abstract: Stacked quantum well light emitting diodes include a plurality of stacked active layers of indium gallium nitride, separated by barrier layers of aluminum gallium nitride or aluminum indium gallium nitride, wherein the ratios of indium to gallium differ in at least two of the stacked active layers. Preferably, the differing ratios of indium to gallium are selected to produce emission wavelengths from the stacked active layers, such that the emission wavelengths are combined to produce white light. Controlled amounts of hydrogen gas are introduced into a reaction chamber during formation of indium gallium nitride or aluminum indium gallium nitride to produce high quality indium gallium nitride or aluminum indium gallium nitride which incorporate large percentages of indium and possesses excellent optical and surface properties.

Abstract: Optoelectronic devices such as photodetectors, modulators and lasers with improved optical properties are provided with an atomically smooth transition between the buried conductive layer and quantum-well-diode-containing intrinsic region of a p-i-n structure. The buried conductive layer is grown on an underlying substrate utilizing a surfactant-assisted growth technique. The dopant and dopant concentration are selected, as a function of the thickness of the conductive layer to be formed, so that a surface impurity concentration of from 0.1 to 1 monolayer of dopant atoms is provided. The presence of the impurities promotes atomic ordering at the interface between the conductive layer and the intrinsic region, and subsequently results in sharp barriers between the alternating layers comprising the quantum-well-diodes of the intrinsic layer.

Abstract: A monolithic Optoelectronic Integrated Circuit including a photodiode and a CMOS readout circuit is described in which the diode is formed by compositionally graded layers of In.sub.x Ga.sub.1-x As selectively epitaxially grown between a substrate of Si and an absorption layer of In.sub.x Ga.sub.1-x As, the areas of said layers being less than 500 .mu.m.sup.2 and wherein a readout circuit on said substrate is coupled to said diode.

Abstract: In order to reduce the dark current due to an interfacial defect and effect higher sensitivity, there is disclosed a manufacturing method for a photoelectric conversion device having a light absorbing layer and a carrier multiplying layer at least having a non-single crystalline semiconductor, the carrier multiplying layer being composed of a plurality of graded layers of which the forbidden band width continuously changes from the minimum forbidden band width Eg1 to the maximum forbidden band width Eg2, wherein there is an energy step sufficient to avalanche multiply the carriers between a region of the maximum forbidden band width Eg2 and a region of the minimum forbidden band width Eg1 adjacent thereto, when an electric field is applied, characterized in that after the deposition of any one of the region of the minimum forbidden band width Eg1 and the region of the maximum forbidden band width Eg2, the plasma treatment is performed with a gas at least containing oxygen or nitrogen, and further the other re

Abstract: A smooth and monotonic potential energy gradient was established at a p-type (InGa)As--undopad InP heterojunction to efficiently transfer conduction electrons from the (InGa)As:p layer to the InP:.o slashed. layer. This potential energy gradient was established with a compositionally graded p-type semiconductor alloy layer and an n-type InP built-in field layer interposed at the heterojunction. The compositionally graded semiconductor alloy layer spatially distributes the conduction band discontinuity of the (InGa)As--InP heterojunction and the InP:n built-in field layer eliminates potential energy barriers from the conduction band over a wide range of externally-applied biases including no externally applied bias. The smooth and monotonic potential energy gradient thus established promotes efficient transfer of the conduction electrons due to drift from the (InGa)As:p layer to the large bandgap InP collector layer where they contribute to the output current of any number of electronic devices.

Abstract: To provide a Schottky junction device having a super-lattice arranged in the Schottky interface in order to secure a high Schottky barrier and at the same time showing a high speed response by resolving the phenomenon of piled-up holes at the upper edge of the valence band, while maintaining the height of the Schottky barrier. A Schottky junction device having a Schottky junction of a semiconductor and a metal and a superlattice on the interface of the semiconductor and the metal, wherein the upper edge of the valence band of said superlattice is varied to show a turn to a specific direction. The phenomenon of hole-piling up at the upper end of the valence band is resolved while maintaining the height of the Schottky barrier and consequently such a Schottky junction device shows an excellent high speed response.

Abstract: Group II-VI compound semiconductor light emitting devices which include at least one II-VI quantum well region of a well layer disposed between first and second barrier layers is disclosed. The quantum well region is sandwiched between first and second cladding layers of a II-VI semiconductor material. The first cladding layer is formed on and lattice matched to the first barrier layer and to a substrate of a III-V compound semiconductor material. The second cladding layer is lattice matched to the second barrier layer. The quantum well layer comprises a II-VI compound semiconductor material having the formula A.sub.x B.sub.(1-x) C wherein A and B are two different elements from Group II and C is at least one element from Group VI. When the second cladding layer has a p-type conductivity, a graded bandgap ohmic contact according to the present invention can be utilized.

Abstract: Compatibility of high sensitivity with low remaining images, and low crosstalk can be achieved by a laminated solid-state image pickup device, which includes accumulating portions for accumulating electric signals, reading units for reading the electric signals, connecting members formed in contact with the accumulating portions, and a photoconductive film, and by a method for manufacturing the device. The photoconductive film is made of a non-crystalline semiconductor, and is configured by laminating a carrier multiplication layer, a light absorbing layer, a charge injection inhibiting layer of a second conduction type. Each of the connecting members is made of a semiconductor layer of a first conduction type, intrinsic or having a low impurity density, surrounded by a semiconductor layer of the second conduction type or a conductive material.

Abstract: The present invention provides a sub-mount type device for emitting light which has high speed response and yet can radiate heat sufficiently. The sub-mount type device for emitting light comprises a heat sink (4), a sub-mount body (62) mounted on the heat sink (4) which comprises an insulating layer (38) with a upper face and a lower face, a upper electrode (42) on the upper face and a lower electrode 44 and 36 on the lower face, the insulating layer having two parts of the insulating layer (38) thickness of which is different, and a chip (30) for emitting light above the thinner part (39) of the insulating layer (38).

Abstract: A quantum well structure is provided which is capable of efficiently confining electrons and holes in a quantum well layer. The quantum well structure includes a first cladding layer, a second cladding layer, and a plurality of quantum well layers and one or more barrier layers each disposed between the first cladding layer and the second cladding layer. The quantum well layers and the barrier layers are laminated in an alternating manner. The quantum well layers include at least two selected from the group consisting of a layer having tensile strain, a layer having no strain, and a layer having compressive strain. The thickness of each of the quantum well layers is selected so that the energy difference in each of the quantum well layers between the ground quantum state of an electron at the conduction band and the ground quantum state of a hole at the valence band is substantially the same.

Abstract: A substrate consisting of a compound semiconductor crystal, a buffer layer, a graded layer, a light-absorbing layer having a lattice constant smaller than that of the uppermost mixed crystal sublayer of the graded layer, a p-type conductive layer, another p-type conductive layer, and a capping layer formed on the surface of the light-absorbing layer next to the p-type conductive layer and having almost the same lattice constant as that of the uppermost layer of the graded layer are stacked. An electrode is connected to the substrate, and another electrode is connected to the conductive layer. A tensile force is applied to the light-absorbing layer from the uppermost mixed crystal sublayer of the graded layer, the capping layer, and the conductive layer, thereby suppressing a dark current.

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 semiconductor photocoupler is composed of a light emitting element and a light receiving element. Wavelength of emitted light changes as a function of exciting current intensity of the light emitting element, and capacitance of the light receiving element changes as a function of wavelength of receiving light and ceases the capacity change as the receiving light disappears. Signals are transmitted in current-light-capacity type transmission with memory action in the light receiving element.

Abstract: The invention provides an avalanche photodiode multilayer structure comprising an absorption layer for absorbing photons and subsequent generation of electron hole pairs, a field relaxation layer in contact with the absorption layer and a multiplication layer in contact with the field relaxation layer. The multiplication layer comprises a plurality of periods of first and second layers. The first layer has a first graded energy band gap being gradually increased in a direction toward which traveling electrons are being accelerated by a predetermined electric field. The second layer has a second graded energy band gap being gradually decreased in the same direction. Both a conduction band edge and a valance band edge are free from any discontinuities and are sloped down toward the same direction through the first and second layers when the first and second layers are being applied with the electric field.

Abstract: A photoelectric conversion device includes a plurality of photoelectric conversion units and a signal output unit. The signal output unit has at least one storage device for storing electrical signals generated by the photoelectric conversion device. A scanning device scans the electrical signals generated by the electric conversion units, and a reading device reads out electrical signals generated by the photoelectric conversion units. Each of the photoelectric conversion units includes a light absorption layer and a multiplication layer. The multiplication layer includes at least one step-back structure which multiplies carriers produced by absorption of light, and in which a forbidden band width changes continuously from a minimum to a maximum width.

Abstract: An infrared LED can function efficiently as both an emitter and a detector at a common wavelength without undesirable characteristics found in avalanche diodes. The LED comprises a graded-bandgap Ga.sub.1-x Al.sub.x As semiconductor material with two semiconductive regions that form a p-n junction. The value of x (the amount of aluminum in the semiconductive material Ga.sub.1-x Al.sub.x As) is varied monotonically as the material is grown so that x decreases monotonically from a value greater than 0.08 at the diode surface on the N side of the p-n junction to a value not less than zero at the diode surface on the P side of the junction. The value of x at the p-n junction is greater than 0 and less than 0.08 as a result of a high initial growth temperature of at least about 930 degrees Celsius. A wavelength matched emitter and detector system is realized by adjusting the present diode's initial growth temperature so that its detector response curve substantially overlaps the emission curve of a second diode.

Abstract: A semiconductor structure useful in blue light emitting diodes and diode lasers is disclosed. The structure is formed of a substrate of p- type GaAs, a layer of a p- type II-VI compound of the formula Zn.sub.x Q.sub.1-x S.sub.y Se.sub.1-x where Q=Mg, Cd or Mn, 0.5.ltoreq.x.ltoreq.1 and 0.ltoreq.y.ltoreq.1, separated from the substrate by a series of thin epitaxial undoped or p-doped layers including a layer of In.sub.0.5 Al.sub.0.5 P in contact with the layer of the II-VI compound, a layer of In.sub.0.5 Ga.sub.0.5 P or of Al.sub.x Ga.sub.1-x As where x=0.1-0.3 contacting the substrate, a layer of In.sub.0.5 Ga.sub.0.5 P contacting the layer of Al.sub.x Ga.sub.1-x P and at least one layer of In.sub.0.5 Al.sub.2 Ga.sub.0.5-z P where 0<z<0.5 and the value of z decreases in the direction of the layer of In.sub.0.5 Ga.sub.0.5 P provided between and contacting the layer of In.sub.0.5 Al.sub.0.5 P and the layer of In.sub.0.5 Ga.sub.0.5 P.

Abstract: An electromagnetic wave detector has several stacks of layers of semiconducting materials. Each stack constitutes an asymmetrical quantum well with stepped barrier and has two energy levels, one of which is located beneath the energy level of the intermediate barrier step while the other is located above it. Means are used to apply an electric field to the structure.

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 semiconductor device with a strained-layer superlattice is disclosed, in which a first semiconductor and a second semiconductor of a lattice constant smaller than that of the first semiconductor are stacked on a clad layer of a lattice constant substantially intermediate between those of the first and second semiconductors to form the strained-layer superlattice. The lattice constant of the strained-layer superlattice in the direction of its plane in the free space is nearly equal to the lattice constant of the clad layer. A third semiconductor of a lattice constant substantially equal to that of the clad layer is laminated between the first and second semiconductors stacked one on the other.

Abstract: Semiconductor devices having a low density of dislocation defects can be formed of epitaxial layers grown on defective or misfit substrates by making the thickness of the epitaxial layer sufficiently large in comparison to the maximum lateral dimension. With sufficient thickness, threading dislocations arising from the interface will exit the sides of the epitaxial structure and not reach the upper surface. Using this approach, one can fabricate integral gallium arsenide on silicon optoelectronic devices and parallel processing circuits. One can also improve the yield of lasers and photodetectors.

Abstract: A semiconductor photodetector device includes a second conductivity type region extending through a first conductivity type window layer to a first conductivity type light absorbing layer and a short carrier lifetime region surrounding ht second conductivity type region such that the lifetime of minority carriers generated in the light absorbing layer outside a depletion layer located around the second conductivity type region is significantly shorter than the lifetime of minority carriers elsewhere within the light absorbing layer. The photodetector device can respond quickly to variations in incident light because the collection of charge carriers generated in the light absorbing layer outside the depletion layer is reduced.

Abstract: A mercury-cadmium-telluride (HgCdTe) photoresponsive layer (14) having the composition Hg.sub.1-x Cd.sub.x Te is formed on a substrate (12) such that x increases from the surface (14a) of the photoresponsive layer (14) toward the substrate (12). This causes the bandgap in the photoresponsive layer (14) to increase from the surface (14a) toward the substrate (12), thereby urging minority carriers which are photogenerated in the photoresponsive layer (14) to move toward and be trapped at the surface (14a). Laterally spaced first and second ohmic contacts (16,18) are electrically connected to the photoresponsive layer (14) at a predetermined distance (z.sub.c) below the surface (14a) such that the photogenerated minority carriers trapped at the surface (14a) are urged away from the contacts (16,18) by the increasing bandgap.

Abstract: An avalanche photodiode having a beryllium guard ring. The beryllium is implanted at a dosage of at least 5.times.10.sup.14 per cm.sup.2 and subsequently annealed to provide a guard ring profile with a p+core and a superlinearly graded tail. The doping profile of the guard ring immediately adjacent the core is superlogarithmic.

Abstract: An electronic bolometer comprises at least a quantum well between two barrier layers. It has an input side parallel to the quantum-well layer and receiving a beam at a quasi-normal incidence angle. Two electrodes disposed perpendicularly to the quantum-well layers allow to measure a change in the resistivity of said quantum well.

Abstract: A photodiode array composed of sharply tuned at consecutively different wavelengths are disclosed with the vertical resonance cavity. Semiconductor superlattice distributed Bragg reflectors can be used as the resonance cavity to achieve sharp tuning and monolithic integration, and the wedged distributed Bragg reflector configuration resonance cavity provides a sequential wavelength detection range. A linear array having resolution a fraction of the photodiodes bandwidth and a square-matrix array with a wedged etalon for high resolution, are disclosed. The disclosed photodiode array make a pocket-type wavelength meter feasible and can be used as a substitute for a spectrometer.

Abstract: A non-linear optical device having the TBQ structure comprises an active layer forming a quantum well for interacting with an incident optical beam, an electron removal layer provided adjacent to the active layer at a first side thereof with a first barrier layer intervening therebetween for removing the electrons from the active layer; and a hole removal layer provided adjacent to the active layer at a second, opposite side of the active layer with a second barrier layer intervening therebetween for removing the holes from the active layer; wherein the first and second barrier layers have respective thicknesses determined such that the probability of tunneling of the electrons through the first barrier layer and the probability of tunneling of the holes through the second barrier layer are substantially equal with each other.

Abstract: This invention pertains to a p-i-n In.sub.0.53 Ga.sub.0.47 As photodiode having an optically transparent composite top electrode consisting of a thin semitransparent metal layer from 10 to 40 nm thick and a transparent cadmium tin oxide (CTO) layer from 90 to 600 nm thick. The metal layer makes a non-alloyed ohmic contact to the semiconductor surface, acts as a barrier between the semiconductor and the CTO preventing oxidation of the semiconductor from the O.sub.2 in the plasma during reactive magnetron sputtering of the CTO layer, and prevents formation of a p-n junction between the semiconductor and CTO. The CTO functions as the n or p contact, an optical window and an anti-reflection coating. The top electrode also avoids shadowing of the active layer by the top electrode, thus allowing greater collection of incident light. Since the top electrode is non-alloyed, inter-diffusion into the i-region is not relevant, which avoids an increased dark current.

Abstract: Carriers are permitted escape from quantum wells within a semiconductor device in the minimum amount of time by utilizing semiconductor material in the barrier layers around the quantum well wherein the barrier layers exhibit an effective bandgap energy less than the sum of the longitudinal optical phonon energy and the exciton absorption energy.

Abstract: Disclosed are novel fast semiconductor photodetector means that comprise a good asymmetric superlattice structure. Associated with the material of the structure is a relatively short minority carrier effective lifetime .tau..sub.e, typically .tau..sub.e <10.sup.-9 sec. In response to a constant photon flux of appropriate wavelength the photodetector can have a substantially constant voltage output that is proportional to the photon flux for small values of flux, and that saturates at a value that is substantially proportional to .tau..sub.e.sup.-1 for relatively large values of flux. The novel photodetector means can be advantageously combined with a FET or bipolar transistor, and the combination can be part of an integrated circuit.

Abstract: An avalanche photodiode includes an avalanche multiplication layer of a hetero-periodical structure consisting of alternately provided barrier and well layers. Each barrier layer includes a multi-quantum barrier layer consisting of alternately provided short-width barrier and well layers. The barrier and well layers include respectively first and second III-group elements which meet the following conditions:E.sub.A <E.sub.B, and E.sub.A +E.sub.gA <E.sub.B +E.sub.gBorE.sub.A <E.sub.B, and E.sub.A +E.sub.gA >E.sub.B +E.sub.gBwhere E.sub.A and E.sub.B are average ionization energies of the first and second III-group elements respectively, and E.sub.gA and E.sub.gB are forbidden band gap energies, respectively.

Abstract: A multiple quantum well superlattice radiation detector is compositionally graded to establish an internal electric field within the superlattice that allows the device to operate with a reduced or zero externally applied bias voltage. The compositional grading can be implemented by grading the doping levels of successive quantum wells or the relative proportions of elements in successive barrier layers of the superlattice, or by a combination of the two. If a tunneling current blocking layer is employed, it can also be compositionally graded to inhibit a substantial increase in the blocking layer's barrier energy level near a charge carrier collector on the other side of the blocking layer from the superlattice. The charge carrier collector can itself be provided with a graded dopant concentration near the blocking layer to inhibit reverse bias voltage breakdown in the blocking layer.

Abstract: A photodiode having a GaInAs light-absorbing layer on an InP substrate which can reduce temperature dependence of the spectral responsivity as well as enable the optical power measurement with less dependence on the incident light spectral width by using a material with smaller composition ratio of Ga for the light-absorbing layer to extend the absorption edge toward the longer wavelengths.

Abstract: Optically pumped coupled quantum well devices are disclosed. The devices store bits as carrier packets in depressions in the conduction and/or valence band(s) of a single crystal; the band between the depressions is sloped in a common direction which provides unidirectionality. The carrier packets are shifted from depression to depression by optically exciting the carriers and relying on the arrangement of depressions and band slopes; the excitation is conveniently performed by laser illumination. The depressions may be sufficiently small to discretize the energy levels and thereby permit the partitioning of the depressions into groups with each group having depressions of substantially the same energy level structure. The carriers in depressions of one group can then be selectively excited by illumination with a laser or narrow band monochromatic incoherent light source tuned to the energy level structure; this allows multiphase operation of the shifting function.

Abstract: A lateral injection group III-V heterostructure device having self-aligned graded contact diffusion regions of opposite conductivity types and a method of fabricating such devices are disclosed. The device includes a heterojunction formed by a higher bandgap III-V compound semiconductor formed over a lower bandgap III-V compound semiconductor. The method of the present invention allows the opposite conductivity type diffusion regions to diffuse simultaneously and penetrate the heterojunction. This results in compositional mixing of the compound semiconductor materials forming the heterojunction in the diffusion regions.