Northrop Grumman Systems Corporation

Westinghouse Electric Corporation

Richard H Hopkins

Donovan L Barrett

Godfrey Augustine

Raymond G Seidensticker, Deceased

Michael W Cresswell

Narsingh Bahadur Singh

Zoltan K Kun

James P McHugh

Robert Mazelsky

Hudson McDonald Hobgood

Walter E Gaida

Vijay Balakrishna

H McDonald Hobgood

R Noel Thomas

Milton S Gottlieb

Richard A Hoffman

Tom Henningsen

Richard N Thomas

Charles S Duncan

Richard D Blaugher

William E Kramer

Pure silicon feedstock is melted and vaporized in a physical vapor transport furnace. In one embodiment the vaporized silicon 46 is reacted with a high purity carbon member 74, such as a porous carbon disc, disposed directly above the silicon. The gaseous species resulting from the reaction are deposited on a silicon carbide seed crystal 50 axially located above the disc, resulting in the growth of monocrystalline silicon carbide 56. In another embodiment, one or more gases, which may include a carbon-containing gas, are additionally introduced at 84 into the furnace, such as into a reaction zone above the disc, to participate in the growth process.

Advanced physical vapor transport method and apparatus for growing high

Method and apparatus for growing semiconductor grade silicon carbide boules (84). Pure silicon feedstock (36) is melted and vaporized. The vaporized silicon is reacted with a high purity carbon-containing gas (64), such as propane, and the gaseous species resulting from the reaction are deposited on a silicon carbide seed crystal (50), resulting in the growth of monocrystalline silicon carbide.

Method and apparatus for growing high purity single crystal silicon

An apparatus for growing single-polytype, single crystals of silicon carbide utilizing physical vapor transport as the crystal growth technique. The apparatus has a furnace which has a carbon crucible with walls that border and define a crucible cavity. A silicon carbide source material provided at a first location of the crucible cavity, and a monocrystalline silicon carbide seed is provided at a second location of the crucible cavity. A heat path is also provided in the furnace above the crucible cavity. The crucible has a stepped surface that extends into the crucible cavity. The stepped surface has a mounting portion upon which the seed crystal is mounted. The mounting portion of the stepped surface is bordered at one side by the crucible cavity and is bordered at an opposite side by the furnace heat path. The stepped surface also has a sidewall that is bordered at one side by and surrounds the furnace heat path. The apparatus may also have a thermal insulating member, in which a side of the stepped surface sidewall opposite to the furnace heat path is bordered by the thermal insulating member.

Method for growing large silicon carbide single crystals

A nitrogen doped single crystal silicon carbide boule is grown by the physical vapor transport process by introducing nitrogen gas into the growth furnace. During the growth process the pressure within the furnace is maintained at a constant value, P.sub.o, where P.sub.o .ltoreq.100 Torr. This is accomplished by measuring the pressure within the furnace and providing the pressure measurement to a process controller which regulates the nitrogen introduction as nitrogen gas is incorporated into the crystal structure. The partial pressure of the nitrogen may be selected to be at a value between 1 and P.sub.o. If the desired partial pressure is less than P.sub.o, an inert gas is added to make up the difference.

Method of making a low resistivity silicon carbide boule

A method of growing 4-H polytype silicon carbide crystals in a physical vapor transport system where the surface temperature of the crystal is maintained at less than about 2160.degree. C. and the pressure inside the PVT system is decreased to compensate for the lower growth temperature.

Method of growing 4H silicon carbide crystal

A silicon carbide feedstock charge for growing silicon carbide boules in a physical vapor transport system. The feedstock charge includes silicon carbide particles, as well as any dopant material, if required, in a structure which is rigid and self supportable. An elongated feedstock charge may be moved toward the seed crystal as the feedstock is depleted during boule growth. The feedstock charge may be tailored to provide a non-uniform flux for growing more planar boule faces.

Feedstock arrangement for silicon carbide boule growth

A method for producing crystals of silicon carbide in a furnace. The furnace has a crucible with a cavity in which the cavity has first and second spaced-apart regions. The crucible cavity of the furnace is capable of being heated, preferably by induction or resistance heating, with insulation placed around the crucible and crucible cavity. A source material of silicon carbide is provided at the first region of the crucible cavity, and a monocrystalline seed is placed at the second region of the crucible cavity. A first growth stage is then conducted in which the first region and the second region of the crucible cavity are heated to at least the sublimation temperature of silicon carbide under substantially isothermal conditions. Then, a second growth stage is conducted in which a temperature gradient is provided between the first and the second region of the crucible cavity, such that the seed in the second crucible region is kept at a temperature lower than a temperature of the first crucible region.

Method of producing large diameter silicon carbide crystals

Apparatus for growing large silicon carbide single crystals

A substrate for use in semiconductor devices, fabricated of silicon carbide and having a resistivity of greater than 1500 Ohm-cm. The substrate being characterized as having deep level impurities incorporated therein, wherein the deep level elemental impurity comprises one of a selected heavy metal, hydrogen, chlorine and fluorine. The selected heavy metal being a metal found in periodic groups IIIB, IVB, VB, VIB, VIIB, VIIIB, IB and IIB.

High resistivity silicon carbide substrates for high power microwave

A crystal of a composition of silver, thallium, and sulfur is useful in non-linear optical devices, acousto-optical devices, piezo electric devices and other types of optical and acoustic devices. The chalcogenide glass composition of the invention displays superior transmission beyond 12 .mu.m.

Chalcogenide glass, associated method and apparatus

A thin film electroluminescent edge emitter assembly includes a substrate layer having a configuration to define at least one lateral edge surface and at least one integrated circuit formed therein. The integrated circuit has an input for receiving logic signals, and has an excitation voltage input and a plurality of output leads. The output leads form control electrodes each having an end portion terminating at the substrate lateral edge surface. The integrated circuit is operable to provide an excitation voltage to selected control electrodes in response to preselected logic signals provided to the integrated circuit at the logic signal input. A laminar arrangement formed from a first dielectric layer, a second dielectric layer, a phosphor layer interposed between the first and second dielectric layers and a common electrode layer is disposed on the end portions of the control electrodes. These various layers define a plurality of pixels each having a light-emitting face at the substrate lateral edge surface. Pixels associated with the selected control electrodes are responsive to the excitation voltage provided to the selected control electrodes to radiate a light signal emitted at the pixel light emitting faces.

Thin film electroluminescent edge emitter structure on a silicon

Thin film electroluminescent edge emitter structure on a silcon substrate

Disclosed is a crystal 1 of thallium arsenic selenide, thallium arsenic sulfide, thallium vanadium sulfide, thallium phosphorous selenide, lead halide, cadmium sulfide, cadmium selenide, cadmium tin arsenide, cadmium germanium arsenide, indium phosphoride, indium arsenide, or mixtures thereof, doped with a precious metal in an amount of about 25 ppm up to the solubility limit of a precious metal in the crystal. The crystal is useful in nonlinear optical devices, acousto-optical devices, piezoelectric devices, and other types of optical and acoustic devices.

Precious metal doped crystals for hardening of the crystals

This is a method of producing grain-oriented, iron sheet for electrical applications. The process utilizes relatively pure iron which is deoxidized to have less than 50 ppm of oxygen. The carbon content is adjusted to 0.01-0.02 wt. % (preferably 0.010-0.015 wt. %). The material is hot rolled at a temperature of at least 800.degree. C., cold rolled with a 60-75% reduction, recrystallized in an non-oxidizing atmosphere at 700.degree.-820.degree. C., cold rolled a second time with a 60-75% reduction, annealed at 700.degree.-825.degree. C. in a non-oxidizing atmosphere and cold rolled a third time with a 60-75% reduction and final annealed at 850.degree.-900.degree. C. for 50-200 hours in a reducing atmosphere.

Development of grain-oriented iron sheet for electrical apparatus

An optical window is provided, particularly for multispectral or broadband wavelength (visible and infrared) transmission, which is resistant to damage or erosion by high velocity raindrops or other adverse environmental conditions. The window consists of a substrate of material having the necessary optical properties for the desired spectral range, with a cladding or protective layer of material of high resistance to erosion or other damage bonded to the substrate by a glass bonding material. While any suitable materials meeting the optical and physical requirements may be used, the substrate may be a material such as zinc selenide with a protective layer of zinc sulfide bonded to the substrate by a thin layer of a chalcogenide glass.

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Murrysville, PA, United States of America

Richard H Hopkins