Westinghouse Electric Corporation

Northrop Grumman Systems Corporation

The United States of America As Represented by the United States

James P McHugh

Raymond G Seidensticker

Narsingh Bahadur Singh

Robert Mazelsky

Richard H Hopkins

Donovan L Barrett

Tom Henningsen

Charles S Duncan

Hudson McDonald Hobgood

Emmanuel P Supertzi

Richard P Storrick

Robert C Miller

Milton S Gottlieb

Paul A Piotrowski

Richard J Ravas

Rolv Hundal

Philip J Nalepa

George V Hall

Chester W Dawson

Maria E Skutch

John A Spitznagel

Frank L Przywarty

Lynd R McCormick

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 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

Crystals formed of Tl.sub.3 AsS.sub.3 provide very good materials for the nonlinear optical conversion efficiency. The crystals are useful in nonlinear optical devices such as harmonic generators and optical parametric oscillators, and in linear applications such as acousto-optical devices. The method of preparing such crystals is also disclosed.

Thallium arsenic sulfide crystals (t1.sub.3 AsS.sub.3) high efficiency

Crystals formed of a solid-solution of Tl.sub.3 AsSe.sub.3 and Tl.sub.1 AsS.sub.3 provide very good materials for the nonlinear optical conversion efficiency. The crystals are useful in nonlinear optical devices such as harmonic generators and optical parametric oscillators, and in linear applications such as acousto-optical devices. The method of preparing such crystals is also disclosed.

Solid solution crystals of Tl.sub.3 AsSe.sub.3 and Tl.sub.3 AsS.sub.3

Acousto-optical devices utilize crystals of a novel material thallium arsenic sulfide (Tl.sub.3 AsS.sub.3) grown from a melt. A Tl.sub.3 AsS.sub.3 crystal is cut and parallel faces are prepared and polished. A piezoelectric transducer connected to an RF generator is placed on the acoustic face to generate sound waves. The light is directed through the optical face of the crystal and interacts with the acoustic waves. These devices may be used in signal processing, spectrum analyzing, spectroscopic, liquid analyzing and spectral imaging systems.

Acousto-optic devices utilizing thallium arsenic sulfide (T1AsS.sub.3)

A melt replenishment system for dendritic web growth having a pellet feed arrangement, which distributes equal amounts of feed material to a pair of feed tubes in communication with opposite ends of a crucible to maintain a melt pool at a constant level and a cover gas system, which keeps the feed tubes flowing and helps maintain thermal consistency within the melt.

Melt replenishment system for dendritic web growth

A method of tailoring the heat balance of the outer edge of the dendrites adjacent the meniscus to produce thinner, smoother dendrites, which have substantially less dislocation sources contiguous with the dendrites, by changing the view factor to reduce radiation cooling or by irradiating the dendrites with light from a quartz lamp or a laser to raise the temperature of the dendrites.

Method of inhibiting dislocation generation in silicon dendritic webs

A method and apparatus for growing dendritic web crystals at increased growth rates is disclosed in which a sublid is used to maintain a sufficiently hot silicon melt surface temperature to insure stable web growth, while simultaneously permitting more efficient heat transfer from the growing dendritic web to the cooler susceptor lid.

Apparatus for dendritic web growth systems

The concept of this invention is to provide a thermal geometry which produces web growth at a constant width by balancing the heat loss pattern from the growing dendrites in such a manner that the outer requirements for stable web growth are simultaneously met. This is accomplished by configuring the geometry of the growth system such that the heat loss pattern from the growing web, the heat loss pattern from the growing dendrites, and the temperature profile in the melt can each be controlled independently and simultaneously optimized.

Apparatus for growing dendritic web crystals of constant width

A melt system including a susceptor-crucible assembly having improved gradient control when melt replenishment is used during dendritic web growth. The improvement lies in the formation of a thermal barrier in the base of the receptor which is in the form of a vertical slot in the region of the susceptor underlying the crucible at the location of a compartmental separator dividing the crucible into a growth compartment and a melt replenishment compartment. The result achieved is a step change in temperature gradient in the melt thereby providing a more uniform temperature in the growth compartment from which the dendritic web is drawn.

Apparatus for growing a dendritic web

Current inrush limiter for incandescent lamps is made by mixing finely divided vanadium sesquioxide and vanadium pentoxide with finely divided glass-forming constituents which include vanadium compound. The mix is compacted and sintered in a substantially inert atmosphere which converts the vanadium oxides to vanadium dioxide maintained in a chemically stable and mechanically strong mass by vitreous binder.

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Wilkins Township, PA, United States of America

James P McHugh