Hughes Aircraft Company

Anthony L Gentile

Oscar Magnus Stafsudd

Douglas A Pinnow

John L Bowers

Antonio C Pastor

Joseph A Wysocki

Robert L Joyce

Sanat K Sashital

Arlie G Standlee

Nanse R Kyle

Fred W Hill

Arthur J Timper

Cylindrical rods of titanium carbide or other refractory material with uniform, high density are prepared by hot pressing plates from powders of the material, with a uniaxial pressing pressure applied to the broad faces of the plate. Bars of square cross section are then cut from the plate and machined to cylindrical rods. The process is particularly suited to the preparation of refractory material preforms to be used in single crystal growth by the float zone method. Titanium carbide rods having a highly uniform density of about 96% that of the theoretical maximum can be readily prepared and then grown into titanium carbide crystals.

Fabrication of rods of uniform high density from powders of refractory

A method for producing a large high-quality single crystal of Cadmium-Indium-Telluride is disclosed wherein a stoichiometric crystal is produced from a non-stoichiometric melt composition. An initial melt composition corresponding to approximately 62 mole % to 90 mole % In.sub.2 Te.sub.3 and 38 mole % to 10 mole % CdTe, respectively, is prepared and sealed in an evacuated ampoule and then heated to completely melt the mixture. Growth of a single crystal of CdIn.sub.2 Te.sub.4 is initiated and maintained from the non-stoichiometric melt mixture by lowering the melt through its corresponding phase-equilibrium melting point. Upon cooling to room temperature, the large single crystal so produced is removed from the ampoule.

Growth of single crystal Cadmium-Indium-Telluride

A method of making a thin, high purity single crystal layer of silver thiogallate. According to the preferred embodiment of this method, a seed crystal substrate of silver thiogallate is dipped into a molten solution of silver thiogallate dissolved in potassium chloride. Upon slowly cooling the solution, the thin layer of single crystal silver thiogallate forms on the substrate. Upon removal, very little of the potassium chloride adheres to the surface, and what does adhere to the surface can be easily removed by washing the surface with hot water.

Silver thiogallate single crystal layers epitaxially grown from

There is disclosed a fiber optic waveguide which is particularly suited for infrared radiation transmission at extended wavelengths. The core of the waveguide is fabricated from heavy ionic compounds selected from metal halides in order to achieve such extended infrared transparency. While it is impossible to prepare these materials into optical fibers using conventional fiber drawing techniques, the present invention teaches how such materials may be prepared into optical fibers using an extrusion process at elevated temperatures and high pressures.

Infrared transmitting fiber optical waveguide extruded from halides of

Disclosed herein is a process for growing II-IV semiconductor crystals which includes providing both a II-IV semiconductor source material and a crystal growth support member in a predetermined dynamic vacuum. This vacuum is sufficient to create a predetermined overpressure at the source material and simultaneously remove impurities therefrom. The temperature of the support member is initally raised to a predetermined level above the temperature of the source material to thereby prevent vapor transport between the two. Then, the temperature of the support member is lowered to a predetermined value below that of the source material to produce a disassociation of elemental gases from the source material and initiate controlled vapor transport of the elemental gases from the source material to the support member. In this manner, compound semiconductor crystals of high purity and stoichiometry are formed on the surface of the support member.

Vapor transport process for growing selected compound semiconductors of

The specification describes a process for growing selected compound semiconductors of high stoichiometry and purity and includes the steps of providing both a dynamic vacuum and a predetermined temperature profile in a container or tube containing a chosen semiconductor source material. The dynamic vacuum is used to create a predetermined minimum overpressure. P.sub.min, in this container with respect to the vapor pressure of the source material, while simultaneously removing impurities through in opening in the container during the crystal growth process. This process involves the vapor transport of elements of the selected compound semiconductor from the source material to a suitable support member, such as a graphite crucible which is maintained at a predetermined uniform controlled temperature. Alternatively, the crystal growth process can be in the form of a vapor phase epitaxial process wherein the selected compound semiconductor is epitaxially deposited on a chosen semiconductor substrate whose temperature is also closely controlled.

There is disclosed a laser instrument which uses an infrared fiber optical waveguide to transmit a high power carbon monoxide or carbon dioxide laser beam for treating a selected part of the body. In one important application of the instrument, the laser beam is transmitted to the interior of the human body to perform surgical functions.

Medical laser instrument for transmitting infrared laser energy to a

Large, strain free, single crystals of high optical quality selected from the IB-VB-VIB and IIIB-VB-VIB ternary chalcogenide groups, having a single stable solid phase from room temperature to the melting point of the crystal and vice-versa, are synthesized by (1) placing stoichiometric quantities of the compound constituents with 3% excess VIB constituent in a two part, sublimation-reaction fused silica tube, the VB constituents being placed in sublimation part, and the remaining constituents being placed in the reaction part, and evacuating and sealing the tube, (2) subliming and purifying the VB constituent and condensing it in the reaction part, which is then cooled and sealed from the sublimation part, (3) reacting, uniting and slowly cooling the reaction part constituents, (4) placing the reacted constituents in fused silica growth tube, which is evacuated, backfilled with helium, and sealed, (5) forming a melt in the upper part of a two part furnace and lowering at about 1.8 mm/hr. through a greater than 100.degree.C temperature gradient, (6) annealing the single crystal in the lower furnace part about one-half the melting point temperature and cooling it to room temperature at about 5.degree.C/hr., and (7) removing the crystal by dissolving the tube in hydrofluoric acid.

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Thousand Oaks, CA, United States of America

Anthony L Gentile