International Business Machines Corporation

George D Pettit

Jerry M Woodall

Peter Daniel Kirchner

Thomas N Jackson

John Lawrence Freeouf

Steven Lorenz Wright

Rodney T Hodgson

Dennis L Rogers

Hans S Rupprecht

Ronald Franklin Marks

Alan C Warren

Thomas O Sedgwick

Richard F Rutz

Eric R Fossum

David T McInturff

James J Rosenberg

Norman Braslau

Peter Oelhafen

Submicron structure fabrication is accomplished by providing vapor chemical erosion of a compound crystal by suppressing the more volatile elements so that the less volatile element is provided with an anti-agglomeration and erosion rate limiting capability which can be followed by subsequent regrowth in the same environment. The erosion is sensitive to crystallographic orientation.

Submicron dimension compound semiconductor fabrication using thermal

An environmental interface for a semiconductor electro-optical conversion device layer that is optically transparent, electrically conductive and chemically passivating, made of an elemental semiconductor with an indirect band gap&gt;1 electron volt in a layer between 20 and 200 Angstroms thick. A GaAs covered by GaAlAs converter with a 100 Angstrom Si layer over the GaAlAs is illustrated.

Semiconductor electro-optical conversion

A semiconductor photodetector is formed of interdigitated, metal-semiconductor-metal electrodes disposed on a surface of semi-insulating semiconductor material, gallium arsenide. Radiation such as infra-red or visible light is converted to an electric current flowing between the electrodes upon application of a bias voltage between the electrodes. A Schottky barrier at the junction of each electrode surface and the semiconductor surface limits current flow to that produced by photons. Tunneling of charge carriers of the current under the Schottky barrier, which tunneling results from the entrapment of charge carriers on the semiconductor surface, is inhibited by the production of a heterojunction surface layer upon the foregoing surface between the electrodes to repulse the charge carriers and prevent their entrapment at the surface. The heterojunction layer may be doped to enhance the repulsion of charge carriers. The heterojunction surface layer is of sufficient thickness to prevent tunneling of photogenerated carriers to a noncontacted region of the surface of the heterojunction layer and to also permit efficient repulsion of charge carriers from the surface. Longer wavelength photodetectors may also be formed in this way by providing misfit dislocation regions between the interaction region, which may be GaInAs, and a GaAs substrate, thereby providing a pseudo-morphic interaction region which is graded back to a heterojunction layer at the surface.

Heterojunction interdigitated schottky barrier photodetector

A layer of an amphoteric dopant on the surface of a group III-V intermetallic semiconductor crystal will diffuse into the crystal surface in a heating cycle forming a stable contact. The contact can be ohmic or rectifying depending on the localized presence of an excess of one crystal ingredient. A layer of Si on GaAs upon heating forms a rectifying contact. When the layer of Si contains As, the contact is ohmic.

Group III-V semiconductor electrical contact

Crystalline compound semiconductors are passivated with a layer of the most volatile element thereof to prevent the formation of oxides that would interfere with further processing. A GaAs crystal is provided with a surface layer of arsenic. The arsenic layer is formed by exposure to light having a photon energy greater than 1.8 eV, at a power density of 0.01 to 0.5 watts per cm.sup.2 while the GaAs immersed in a 1:1 HCl:H.sub.2 O solution for a period of 10-30 minutes. The intermediate processing passivated GaAs crystal may be stored and handled in air and the As layer is removed by low temperature baking.

Intermediate passivation and cleaning of compound semiconductor surfaces

A 10.sup.-6 ohm cm.sup.2 ohmic contact is provided by formation of a 20-50 Angstroms deep surface region with a net donor density of higher than 5.times.10.sup.19 /cc. An amphoteric dopant of Si or Ge is incorporated in a pinned Fermi level condition so that an enhanced surface donor concentration occurs.

Intermetallic semiconductor ohmic contact

A quantity of silicon serving as a source of the element silicon for use in a molecular beam epitaxial growth apparatus where the silicon is in the form of a monocrystalline wafer with a plurality of electrically parallel filaments separated by slots that pass completely through the wafer, each filament having a length dimension that is greater than the width and height dimensions, joined at a broad contact area at each filament end and where an electric current is passed through the filaments through the broad contact areas.

Silicon source component for use in molecular beam epitaxial growth

When growing GaAs by molecular beam epitaxy (MBE), a typical related reaction acts to affix Ga.sub.2 O.sub.3 to the growth surface and hence incorporates such oxide contaminants in the epitaxial layer as it is grown. Such contaminants may yield crystals of poor electrical and optical properties. When Al is added to the Ga source crucible, the Ga.sub.2 O flux is reduced substantially thereby suppressing the formation of such oxide contaminants and remove a serious constraint to MBE growth. When doping GaAs with Mg to form a p-type GaAs layer, unity Mg doping efficiency is achieved by including 0.1% Al in the Ga effusion cell. Such an inclusion of Al improves the Mg doping efficiency by suppressing the formation of MgO, and allows MBE growth at lower substrate temperatures and at higher growth rates.

Volatile metal oxide suppression in molecular beam epitaxy systems

A semiconductor device of the ballistic type, wherein the carrier transport in the body of the device from one electrode to the other takes place essentially free of collisions, is fabricated with a semiconductor body having a long mean-free path, a body width between ohmic electrodes that is less than or equal to the product of the velocity of a carrier and the time to a collision, but more than the distance that will permit quantum mechanical tunnelling, an impressed voltage less than required for an intervalley carrier transition and having the ohmic external contact on each surface of the body free of any barrier to carrier flow. A ballistic type triode device is provided with a current modulating electrode included within the body of the device. The triode device body is of n type conductivity gallium arsenide containing a zinc doped p type conductivity gallium arsenide current modulating inclusion in the body and having, as at least one ohmic external contact, a graded bandgap indium gallium arsenide region.

Semiconductor ballistic transport device

The disclosure provides for the use of a group II-VI compound semiconductor as a surface passivator to control recombination of charge carriers at the surface of a group III-V compound semiconductor by a localized heating step. It is theorized for practice of the invention that the control of the recombination of the charge carriers is achieved by chemical reaction of the II-VI compound with excess group V element. In particular the disclosure provides for the use of a capping layer of laser annealed ZnS as a passivating layer on a GaAs device.

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Mahopac, NY, United States of America

George D Pettit