Bell Telephone Laboratories

At&t Bell Laboratories

At&t Technologies, Inc.

American Telephone & Telegraph Co., At&t Bell Laboratories

American Telephone and Telegraph, Co.

Murray Robbins

John T Plewes

David W Johnson, Jr

Nathaniel R Quick

Patrick K Gallagher

Joachim J Hauser

Edwin Arthur Chandross

Alan Michael Lyons

Barry Irwin Miller

Richard C Sherwood

Ernst M Gyorgy

Adam Heller

Cletus W Wilkins, Jr

Harold Schonhorn

Albert Anthony Ballman

Sau-Lan L Ng

Amiram Appelbaum

Raymond C Stoffers

Frederick T Mendenhall, Jr

Kostantinos Kourtakis

Andreas Leiberich

Annemarie Staudinger

A new technique for forming non-rectifying electrical contacts to III-V semiconductor materials, without the use of dopants or of an alloying procedure, is disclosed. In accordance with this technique, an electrical contact is formed simply by depositing a region of material (onto the semiconductor material) having a composition which includes at least one metal element and at least one of three specific Group V elements, i.e., P, As, or Sb, and having a bulk electrical resistivity equal to or less than about 250 .mu..OMEGA.-cm. Alternatively, a contact is formed by depositing nickel, or a nickel-containing material essentially free of gold and silver, and having a composition which does not include any of the three Group V elements. The nickel, or nickel-containing material, is then reacted with the substrate to form a compound having a composition which includes nickel as well as one of the three Group V elements.

Method for fabricating devices in III-V semiconductor substrates and

A novel method of producing mixed metal oxide powder (e.g., ferrite powder, or high temperature superconductor powder such as YBa.sub.2 Cu.sub.3 O.sub.x powder) is disclosed. The method comprises forming an intimate mixture of appropriate metal salts (e.g., nitrates and acetates), at least one of which is an oxidizing agent with respect to at least one of the others, and heating the mixture to a reaction temperature such that an exothermic redox reaction occurs. Appropriate choice of oxidizing and reducing agents permits control of heat of reaction and reaction temperature. The product of the reaction typically is a precursor of the desired mixed oxide, the precursor typically consisting essentially of the metal constituents of the mixed oxide and oxygen. Heat treatment in an O.sub.2 -containing atmosphere transforms the precursor into the desired mixed oxide powder. The thus produced powder can then be used in conventional fashion, e.g., to produce bodies therefrom by pressing and/or sintering.

Method of producing mixed metal oxide material, and of producing a body

Contacts comprising nickel and a glass-forming additive have electrical contact properties which render them suitable as replacements for gold contacts; disclosed contacts have low contact resistance even after prolonged exposure to an oxidizing ambient. The glass-forming additive is one or several of the elements boron, silicon, germanium, phosphorus, arsenic, antimony, or bismuth, and contacts are readily formed, e.g., as layers on substrates. A crystallographically disordered structure is produced in a contact surface layer at least upon exposure to an oxidizing ambient; alternatively, such desired structure can be produced by ion bombardment and even in the absence of glass-forming additives.

Nickel-based electrical contact

Nickel material comprising controlled amounts of hydrogen has low electrical contact resistance even after prolonged exposure to an oxidizing ambient. When used as a surface layer on an electrically conducting member, such material is suitable as a contact material and represents an inexpensive alternative to gold. And, when prepared in the form of microscopic flakes, such material is suitable for use in electrically conductive inks and adhesives.

Electrically conductive paths are produced on a polymeric substrate by laser writing, i.e., by tracing desired paths on the substrate by a laser beam. The resulting paths comprise electrically conductive carbon as produced by thermal decomposition of substrate surface material; the paths can serve; e.g., as electrical interconnections akin to printed circuitry on a wiring board. Optionally, the conductivity of paths can be enhanced by electroplating a suitable conductor metal or alloy onto the paths.

Direct writing of conductive patterns

Inexpensive Mn or Mg ferrites may be used as negative temperature coefficient thermistors. Fabrication of devices with the desired high temperature coefficients is facilitated by a processing method which forms a thin layer of oxidized and high resistivity material on a low resistivity layer of ferrite material.

Negative temperature coefficient thermistors

A method for electroplating a nickel-antimony alloy comprising from 1-70 weight percent antimony and the balance nickel comprises electroplating the alloy from a solution containing a soluble nickel salt and a soluble mixed antimony alkali metal salt of a polybasic organic acid at a pH in the range of about from 1 to 6. The substrate to be plated is made the cathode and an inert anode is employed.

Method of making non-precious metal electrical contacts by electroplating

A method of producing III-V materials by reducing a complex salt in a hydrogen atmosphere is shown. For example, complex salts reduce to InP or GaAs. The salts are conveniently prepared by coprecipitation from a salt solution or by other methods. The stoichiometry can be modified by applying an overpressure of the more volatile element or elements during reduction.

Preparation of III-V materials by reduction

A carbon transmitter utilizes an electrode prepared by in situ reaction between substrate copper and introduced sulfur. Good surface adhesion between the resulting CuS layer and the substrate is assured by use of a two-phase cobalt/copper substrate.

Carbon transducer with electrical contact

Magnetic material is made by reducing an oxide powder compact having at least one nonreducible oxide species. A typical mixture of nickel, iron, and aluminum oxides selectively reduces to form a material having a typical permeability of 10 or more and high resistivity. Reduced eddy current losses occur in devices made from such material.

Magnetic devices by selective reduction of oxides

In the interest of mechanical strength and hardness, metallic bodies desirably contain dispersed particles whose diameter preferably is in the range of 50-10,000 Angstrom. A disclosed method for producing such metallic bodies calls for preparing a solution of mixed salts of elements, removing the solvent, transforming to metallic form, and compacting under pressure. Strength of a resulting metallic body may be further developed by aging and, optionally, cold deformation prior to aging. Use of the disclosed method is indicated especially to produce bodies comprising immiscible elements. For example, when Mo is dispersed in Cu, high strength and electrical conductivity are realized.

Manufacture of high-strength metallic articles

Desirable properties of manganese zinc ferrites are obtained without the need for controlling or changing the oxygen partial pressure during the sintering and cooling steps by adding a small amount of germanium or gallium to the ferrite and using an atmosphere, such as air, during the sintering and cooling steps, that has at least 1 percent oxygen by volume.

Method of making MnZn ferrites

In the process of producing metal alloy parts by the reduction of powder metal oxide compacts, it has been discovered that single phase alloy parts may be produced by an agglomerated mixture of metal oxides without a separate annealing step. The metal oxide mixture is formed into agglomerates by spray drying a solution of metal salts which are subsequently decomposed, or other techniques, compacted to the desired shape, and then reduced in a hydrogen atmosphere at high temperature. In the case of alloys that would otherwise segregate, a quenching step follows the reduction of the metal oxide shape. As only oxides are involved prior to reduction, problems with surface oxidation are avoided. A sintering step in air can be used to give the oxide compact structural integrity before reduction.

Production of single phase alloy parts by reduction of oxides

A process is described for producing fine particles of certain double oxide compounds. This procedure is advantageous because of the fine particles produced and the accurate stoichiometry of the resulting product. The process is particularly applicable to the production of such compounds as LiNbO.sub.3 and LiTaO.sub.3 and other compounds where conventional procedures involving heating a mixture of individual oxides leads to stoichiometry problems because of the volatility of one of the component oxides.

Process for producing lithium niobate and lithium tantalate

Liquid-semiconductor photocells have received attention recently for use in solar power devices. Alternatives to single crystal semiconductors have been sought to reduce the cost of the photocells. According to this invention, the semiconductor is made from a pressure sintered and vapor annealed semiconductor. The electrode is relatively inexpensive to make and the efficiency of the solar cell compares favorably to the efficiency of solar cells using single crystal electrodes.

Growing community of inventors

Berkeley Heights, NJ, United States of America

Murray Robbins