Patents by Inventor Leo Esaki
Leo Esaki has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 5296048Abstract: A new semiconductor material or compound and method for its manufacture is disclosed. The material or compound has the Formula III-V or IV which includes as part of the compound, a transition element or a rare earth element present in an amount sufficient to change the material or compound from a paramagnetic state to a locally ordered magnetic state. The material or compound is made by depositing III, and V or IV and a transition element or a rare earth element onto a substrate at conditions such that the transition element or rare earth element that is deposited on the substrate is not in equilibrium with the material or compound. By employing this technique new semiconductor materials or compounds can be made including Ga.sub.1-x Mn.sub.x As and In.sub.1-x Mn As where Mn is present in an amount greater than about 5.4.times.10.sup.20 cm.sup.-3.Type: GrantFiled: March 9, 1993Date of Patent: March 22, 1994Assignee: International Business Machines CorporationInventors: Leroy L. Chang, Leo Esaki, Hiro Munekata, Hideo Ohno, Stephan vonMolnar
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Patent number: 5294287Abstract: A new semiconductor material or compound and method for its manufacture is disclosed. The material or compound has the Formula III-V or IV which includes as part of the compound, a transition element or a rare earth element present in an amount sufficient to change the material or compound from a paramagnetic state to a locally ordered magnetic state. The material or compound is made by depositing III, and V or IV and a transition element or a rare earth element onto a substrate at conditions such that the transition element or rare earth element that is deposited on the substrate is not in equilibrium with the material or compound. By employing this technique new semiconductor materials or compounds can be made including Ga.sub.1-x Mn.sub.x As and In.sub.1-x Mn.sub.x As where Mn is present in an amount greater than about 5.4.times.10.sup.20 cm.sup.-3.Type: GrantFiled: August 2, 1991Date of Patent: March 15, 1994Assignee: International Business Machines CorporationInventors: Leroy L. Chang, Leo Esaki, Hiro Munekata, Hideo Ohno, Stephan vonMolnar
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Patent number: 5079601Abstract: The present invention is directed to novel optoelectronic devices, such as light emitters and detectors, that have a unique combination of semiconductor materials that provides a band arrangement resulting in improved efficiency of carrier injection. The devices are quantum well type devices in which discrete electronic states are formed by size quantization effects in the quantum well region. Electromagnetic radiation of emission and absorption occurs by the transition of electrons from a first energy state to a second energy state in either the conduction band or the valence band of the quantum well layer. The bands edges of the layers are offset such that under an appropriate bias, the discrete energy states reside in the bandgap of one of the electrodes and in an allowed region of the other electrode, with one state residing in the conduction band of one electrode and the other state residing in the valence band of the other electrode.Type: GrantFiled: December 20, 1989Date of Patent: January 7, 1992Assignee: International Business Machines CorporationInventors: Leo Esaki, Hideo Ohno, Emilio E. Mendez
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Patent number: 4743951Abstract: The mobility of carriers in the channel region of a field effect transistor can be increased by providing a layered structure wherein electrons are separated from impurities. The channel is made up of external layers of wide bandgap material and internal layers with a narrower bandgap where the bottom of the conduction band of one layer is below the top of the valence band of the adjacent layer. A structure is shown with a layered channel having AlSb external layers and at least one or both of InAs and GaSb internal layers.Type: GrantFiled: March 8, 1982Date of Patent: May 10, 1988Assignee: International Business Machines CorporationInventors: Chin-An Chang, Leroy L. Chang, Leo Esaki, Emilio E. Mendez
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Patent number: 4733282Abstract: A semiconductor superlattice is provided with a one-dimensional quantum pipeline type carrier path. The pipeline is formed at the intersection of different energy level layers of the superlattice. Conductivity modulation through an adjacent exposed surface is employed for control in the pipeline and in arrays thereof. The pipeline carrier path involves both electrons and holes. A structure of Ga.sub.1-x Al.sub.x As with alternating 100.ANG. and 500.ANG. thick layers of different x has positioned, intersecting those layers, a 100.ANG. thick GaAs layer covered by a GaAlAs layer. Control and contacting electrodes are positioned on the exposed surfaces.Type: GrantFiled: August 13, 1985Date of Patent: March 22, 1988Assignee: International Business Machines CorporationInventors: Leroy L. Chang, Leo Esaki
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Patent number: 4665415Abstract: A field-effect transistor includes a conduction channel between a source terminal and a drain terminal, which channel employs holes as the charge carriers. The conduction channel is disposed within a layer of material comprising a group III-V compound of the periodic table and having a crystalline lattice structure which is stressed in two dimensions by means of epitaxial growth upon a thicker and rigid supporting layer comprising a different group III-V compound having a larger lattice spacing. The layer having the conduction channel is relatively thin being on the order of a few electron wavelength in thickness. The stretching of the layer having the conduction channel shift the energy levels of holes therein to remove the degenerate state thereof, thereby elevating light holes to an energy level characterized by increased mobility.Type: GrantFiled: April 24, 1985Date of Patent: May 12, 1987Assignee: International Business Machines CorporationInventors: Leo Esaki, Leroy L. Chang, Wen-I Wang
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Patent number: 4558336Abstract: Misfit dislocation density at an InAs-GaAs interface is reduced in both InAs-GaSb and In.sub.1-x Ga.sub.x As-GaSb.sub.1-y As.sub.y superlattices grown on GaAs substrates by means of an MBE (molecular beam epitaxy) growth technique consisting of a step graded sequence of composition layers between substrate and superlattice whose composition changes in discrete concentration steps from the composition of the substrate to the composition of the superlattice.Type: GrantFiled: March 2, 1984Date of Patent: December 10, 1985Assignee: The United States of America as represented by the Secretary of the ArmyInventors: Chin-An Chang, Leroy L. Chang, Leo Esaki
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Patent number: 4538165Abstract: The mobility of carriers in the channel region of a field effect transistor can be increased by providing a layered structure wherein electrons are separated from impurities. The channel is made up of external layers of wide bandgap material and internal layers with a narrower bandgap where the bottom of the conduction band of one layer is below the top of the valence band of the adjacent layer. A structure is shown with a layered channel having AlSb external layers and at least one or both of InAs and GaSb internal layers.Type: GrantFiled: March 5, 1984Date of Patent: August 27, 1985Assignee: International Business Machines CorporationInventors: Chin-An Chang, Leroy L. Chang, Leo Esaki, Emilio E. Mendez
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Patent number: 4517047Abstract: Misfit dislocation density at an InAs-GaAs interface is reduced in both I-GaSb and In.sub.1-x Ga.sub.x As-GaSb.sub.1-y As.sub.y superlattices grown on GaAs substrates by means of a MBE (molecular beam epitaxy) growth technique consisting of a step graded sequence of composition layers between substrate and superlattice whose composition changes in discrete concentration steps from the composition of the substrate to the composition of the superlattice.Type: GrantFiled: January 23, 1981Date of Patent: May 14, 1985Assignee: The United States of America as represented by the Secretary of the ArmyInventors: Chin-An Chang, Leroy L. Chang, Leo Esaki
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Patent number: 4395722Abstract: A heterojunction transistor device having emitter and collector regions of a first conductivity type separated by an ultra-thin base region of a second conductivity type. Abrupt heterojunctions are formed which are then heat treated to allow the formation of graded heterojunctions exhibiting rectifying characteristics. Typically, the emitter and collector regions are comprised of GaSb while said base region is comprised of InAs. The band gap of the emitter region is selectively chosen to be relatively wide in comparison to the band gap of the base region. Moreover, the band gap of the emitter and collector regions is substantially equal to the conduction band discontinuity between the emitter and base, and the band gap of the base is substantially equal to the valance band discontinuity and the edge of the conduction band of the base region is substantially coincident with the edge of the valance band of the emitter region.Type: GrantFiled: October 21, 1980Date of Patent: July 26, 1983Assignee: The United States of America as represented by the Secretary of the ArmyInventors: Leo Esaki, Chin-An Chang
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Patent number: 4371884Abstract: Disclosed is a tunnel diode consisting of an accumulation region of p-type GaSb and an accumulation region of n-type InAs separated by a thin layer of a quaternary compound consisting of InGaSbAs. Such a diode structure converts the interface between the two accumulation regions of p-type and n-type material from what would normally be an ohmic junction into a tunneling junction. Such a tunnel diode requires no heavy doping which is normally required for a tunnel diode.Type: GrantFiled: January 23, 1981Date of Patent: February 1, 1983Assignee: The United States of America as represented by the Secretary of the ArmyInventors: Leo Esaki, Chin-An Chang
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Patent number: 4348686Abstract: A detector and/or mixer of electromagnetic energy in the microwave-infrared region of the electromagnetic spectrum comprised of a body of semiconductor material having a superlattice region consisting of, for example, InAs - GaSb wherein the thickness of alternating epitaxial planar layers is in the range of 30A to 80A. Incident radiation perpendicular to the planar regions results in an electric field being provided in the plane of the layers which causes a reduction in the superlattice bandwidth and accordingly an increase in the transverse effective mass of the carriers. This results in a decrease in the perpendicular conductivity through the superlattice region.Type: GrantFiled: July 28, 1980Date of Patent: September 7, 1982Assignee: The United States of America as represented by the Secretary of the ArmyInventors: Leo Esaki, George A. Sai-Halasz
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Patent number: 4250515Abstract: A superlattice structure is disclosed in which alternating layers of semiductor alloy materials provide a one dimensional spatial periodic variation in band edge energy. A first layer of the superlattice device is an alloy including a first Group III material and a first Group V material, preferably In As, while the second layer is an alloy including a second Group III material different from the first Group III material and a second Group V material different from the first Group V material, and preferably GaSb. In the superlattice structure the valence band of the second alloy is closer to the conduction band of the first alloy than it is to the valence band of the first alloy.Type: GrantFiled: June 9, 1978Date of Patent: February 10, 1981Assignee: The United States of America as represented by the Secretary of the ArmyInventors: Leo Esaki, Raphael Tsu, George A. Sai-Halasz, Leroy L. Chang
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Patent number: 4239584Abstract: A system and method including the use of hydrogen in the molecular beam evaporation process for epitaxy growth, such as in the formation of GaAs and GaAlAs and Sn for n-type dopant impurity. In a molecular beam epitaxy system, a hydrogen beam introduced and, along with the molecular beam, is directed on the substrate during the epitaxy growth such that the presence of the relatively small volume of hydrogen influences the physical surface properties of the epitaxially grown material and therefore the quality of the epitaxy.Type: GrantFiled: September 29, 1978Date of Patent: December 16, 1980Assignee: International Business Machines CorporationInventors: Chin-An Chang, Leroy L. Chang, Leo Esaki
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Patent number: 4208667Abstract: A heterojunction structure made of two semiconductor layers is disclosed in hich light is applied to the structure and absorbed, and the emission of light from the structure is controlled by an electric field applied perpendicularly to the planes of the layers. It is further disclosed that the device can be employed as a selective light filter or modulator.Type: GrantFiled: June 9, 1978Date of Patent: June 17, 1980Assignee: The United States of America as represented by the Secretary of the ArmyInventors: Leroy L. Chang, Leo Esaki, George A. Sai-Halasz
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Patent number: 4205331Abstract: An optical device is disclosed which includes first and second superlattice emiconductor regions. The first superlattice semiconductor region includes a plurality of alternating barrier and light absorbing layers which absorbs light of a first light frequency. The second superlattice region also includes a plurality of alternating barrier and light absorbing layers. However, the light absorbing layers of the second superlattice semiconductor region absorbs light of a different frequency.Type: GrantFiled: June 9, 1978Date of Patent: May 27, 1980Assignee: The United States of America as represented by the Secretary of the ArmyInventors: Leo Esaki, George A. Sai-Halasz, Leroy L. Chang
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Patent number: 4198644Abstract: A tunnel diode is disclosed wich includes a heterostructure consisting of a irst layer of GaSb.sub.1-y As.sub.y and a second layer of In.sub.1-x Ga.sub.x As. It is also disclosed that other alloys of Group III and Group V materials can be employed in a tunnel diode of the instant invention.Type: GrantFiled: June 9, 1978Date of Patent: April 15, 1980Assignee: The United States of America as represented by the Secretary of the ArmyInventor: Leo Esaki
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Patent number: 4173763Abstract: Device having three semiconductor regions, which can be characterized as the emitter, base and collector regions. The emitter and collector regions have a first conductivity type, and the base region has the opposite conductivity type, where both the base-emitter and base-collector junctions are heterojunctions. The base region is sufficiently thin that charge carriers can tunnel therethrough. The base region has a small resistance due to its heavy doping (which is greater than the doping of both the emitter and the collector). Both the valence band and the conduction band in the emitter and collector regions are shifted in the same direction with respect to the valence band and conduction band of the base region (i.e., the energy gaps of the emitter and collector are shifted in the same direction with respect to the energy gap of the base region and overlap with the energy band of the base to produce band-edge discontinuities .DELTA.E.sub.c and .DELTA.E.sub.v).Type: GrantFiled: June 9, 1977Date of Patent: November 6, 1979Assignee: International Business Machines CorporationInventors: Leroy L. Chang, Leo Esaki
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Patent number: 4163238Abstract: It is taught that infrared light can be produced by applying a voltage to a semiconductor device with a superlattice region and, further, that a population inversion can be achieved in such a device so that infrared amplification and oscillation can be produced. Methods of producing infrared radiation and of amplifying infrared radiation utilizing semiconductor devices with superlattice regions are disclosed. Also, semiconductor devices with superlattice regions for use as a laser amplifier or oscillator are taught.Type: GrantFiled: June 9, 1978Date of Patent: July 31, 1979Assignee: The United States of America as represented by the Secretary of the ArmyInventors: Leo Esaki, Raphael Tsu
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Patent number: 4137542Abstract: A semiconductor structure may be fabricated that confines current flow to two dimensions by constructing as a structure a body of alternate regions of different semiconductor materials with current flow parallel to the intersections of the regions. The structure, in device form, exhibits the properties of selectable energy gap, higher carrier mobility and increased electronic density of states. Such devices are usable for their bulk properties, their junction electro-optical properties and their junction transistor properties.Type: GrantFiled: April 20, 1977Date of Patent: January 30, 1979Assignee: International Business Machines CorporationInventors: Leroy L. Chang, Leo Esaki