US2766508A - Blocking layer for titanium oxide rectifier - Google Patents

Blocking layer for titanium oxide rectifier Download PDF

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US2766508A
US2766508A US289248A US28924852A US2766508A US 2766508 A US2766508 A US 2766508A US 289248 A US289248 A US 289248A US 28924852 A US28924852 A US 28924852A US 2766508 A US2766508 A US 2766508A
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layer
titanium
rectifier
plate
partially oxidized
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US289248A
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Loup Theodore E Le
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General Electric Co
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General Electric Co
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Priority to GB13888/53A priority patent/GB736251A/en
Priority to GB13887/53A priority patent/GB733267A/en
Priority to BE520122D priority patent/BE520122A/xx
Priority to FR1083556D priority patent/FR1083556A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/34—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies not provided for in groups H01L21/0405, H01L21/0445, H01L21/06, H01L21/16 and H01L21/18 with or without impurities, e.g. doping materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B7/00—Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor
    • B24B7/10—Single-purpose machines or devices
    • B24B7/16—Single-purpose machines or devices for grinding end-faces, e.g. of gauges, rollers, nuts, piston rings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H01L29/24—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only semiconductor materials not provided for in groups H01L29/16, H01L29/18, H01L29/20, H01L29/22
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/43—Electric condenser making

Definitions

  • Thisinve'ntion relates to a titanium dioxideal ternating current rectifier; more particularly, it refers to a titanium dioxide rectifier having a blocking layer applied-by electrolytic anodization.
  • a titanium dioxide rectifier is described together with a method for producing such a rectifier.
  • a titanium rectifier is produced by heat treating a titanium plate in an atmosphere containing oxygen to produce an oxide layer, further treating the titanium plate to partially reduce the oxide layer, and applying over the partially reduced oxide layer a counterelectrode composed of a metal having a high work function.
  • a titanium plate is subjected to a heat treatment' in an oxidizing, or partially oxidizing, atmosphere to produce an oxide layer over at least a portion of the titanium plate surface.
  • the partially oxidized layer is then subjected to an electrolytic anodization treat ment to provide a thin uniform blocking layer of oxide to which an overlying layer of counterelectrode metal having a high work function is then applied.
  • a base electrode 10 is composed of a titanium plate thick enough to impart rigidity to the device. Overlying all or a part of the titanium plate 10 is a'partially oxidized layer 11. Theexposed surface of the layer 11 is subjected to an electrolytic anodization treatment which results in the formation of a thin layer 12 of oxide. Overlyingall or a portion of the layer 12 is a counterelectrode layer 13 composed of a metal having a high work function.
  • the thickness of the layers 11, 12 and 13 is greatly exaggerated for purposes of clarity of illustration.
  • the layers 11 and 12 are normally less than a thousandth of an inch in thickness and the layer 13 may be of the order of a thousandth of an inch.
  • the base electrode 10 may be much thinner than it is shown in the illustration.
  • the titanium plate 10 In preparing a titanium dioxide rectifier in accordance with my invention, the titanium plate 10 must have a clean surface. This may be obtained by subjecting a plate to an abrasive process or by treatment in an acid solution. A satisfactory acid solution in which the plate may be immersed consists of 80% nitric acid and hydrofluoric acid.
  • the plate is then subjected to a heat treatment in an atmosphere containing oxygen.
  • the oxygen containing atmosphere is provided by steam
  • reducing action is provided by the hydrogen produced-in the decomposition of the water vapormolecule.
  • two atoms of reducing hydrogen are produced.
  • the steam treatment produces a layer 11. having-minute particles of titanium dispersed therethrough.
  • the layer 11 should preferably have-a thickness of the'orderof 0.0005".
  • the base electrode 10 is shown with the layer 11 coveringa portion of one surface thereof, in practice the layer. 11 covers the entire surface of the titanium base 10 since it is most easily manufactured with this construction.
  • the layer 11' is subjectedto an electrolytic anodization in order to provide a block-v ing layer. of oxide.
  • an oxide layer applied by electrolytic anodization is self-insulating.
  • no more current will flow through this portion and further oxidation, if any, will takeplace only on portions of the surface having a thinner oxide layer. This action re sul'tsin. an. oxide layer of uniform thickness over the entire surface.
  • Anodizing solutions are well known in the electrolytic art. Solutions of sodium hydroxide, potassium hydroxide, chromic: acid, ammonium hydroxide, and sul-. furic acid are all satisfactory for purposes of. applying an oxide blocking layer to the partially oxidized layer 11. I have obtained best results from the use of a sodium hydroxide solution of about 10 to 17 percent concentration.
  • the base electrode 10 is made the anode in such a solution.
  • the current density is a function of time (at constant voltage) and the back voltage of the cell is dependent on the final current density.
  • the anodization is preferably accomplished by gradually increasing the potential to about 40 volts while keeping the current at about 5 ma./cm. Under continued application of 40 volts, the current decreases to a range of 5-20 ma. on a plate 1" x
  • the anodization may be carried out with the solution at room temperature.
  • the counterelectrode 13 is applied by any method which will insure the close union of the layers 12 and 13.
  • I method of effecting a close union between the layers 12 and 13 is dependent to some extent upon the nature of the counterelectrode metal used. Certain metals may be applied in a molten state while others are best applied by vapor deposition. In general, vapor deposition is a preferred method of applying the layer 13.
  • the counterelectrode 13 is composed of a metal having a high work function.
  • Bismuth, nickel, and platinum fulfill these requirements whereas cadmium, zinc, tin, aluminum, and magnesium when used as counterelectrodes, produce a rectifier which is considerably inferior to a rectifier having a counterelectrode composed of bismuth, nickel, or
  • the partially oxidized titanium is an 11 type semi-conductor with the free titanium contributing the electron conduction.
  • the counterelectrodes of bismuth, nickel, or platinum all have missing electrons in their d shells which contribute holes for a p conduction.
  • the other metals mentioned do not have missing electrons in their d shells.
  • the term high work function includes metals having missing electrons in their at shells which contribute holes for p type conduction.
  • the deposition of the counterelectrode on the n type titanium establishes a p-n junction.
  • a thin insulating layer or a layer with fewer n or p carriers between the n type region and the p type region. This layer reduces the leakage and raises the reverse voltage of the rectifiers.
  • a rectifier made in accordance with my invention has superior high temperature stability and compares favorably with other rectifiers from the standpoint of current loading and voltage rating.
  • the method of preparing a titanium dioxide rectifier which comprises forming a partially oxidized layer on a surface of a titanium plate by heating said plate in an atmosphere containing oxygen, forming a layer of oxide on said partially oxidized surface by electrolytic anodization and applying to said oxide layer a counterelectrode metal having a high work function.
  • the method of preparing a titanium dioxide rectifier which comprises forming a partially oxidized layer on a surface of a titanium plate by heating said plate to a temperature in excess of 600 C. in an atmosphere of steam for four hours, forming an oxidized layer on said partially oxidized layer by electrolytic anodization and applying to said oxidized layer a counterelectrode metal having a high work function.
  • the method of preparing a titanium dioxide rectifier which comprises forming a partially oxidized layer on a surface of a titanium plate by heating said plate in an atmosphere containing oxygen, forming an oxidized layer on said partially oxidized layer by electrolytic anodization in an aqueous sodium hydroxide bath and applying to said oxidized layer a counterelectrode metal having a high work function.
  • the method of preparing a titanium dioxide rectifier which comprises forming a partially oxidized layer on a titanium plate by heating said plate in an atmosphere containing oxygen, forming an oxidized layer on said partially oxidized layer by electrolytic anodization in a chromic acid solution and applying to said oxidized layer a counterelectrode metal having a high work function.
  • the method of preparing a titanium dioxide rectifier which comprises forming a partially oxidized layer on the surface of a titanium plate by heating said plate in an atmosphere containing oxygen, forming an oxidized layer on said partially oxidized layer by electrolytic anodization in an ammonium hydroxide solution and applying to said oxidized layer a counterelectrode metal having a high work function.
  • the method of preparing a titanium dioxide rectifier which comprises forming a partially oxidized layer on a surface of a titanium plate by heating said plate to a temperature between 600 C. and 700 C. in an atmosphere of steam for about four hours, forming an oxidized layer on said partially oxidized layer by electrolytic anodization in sodium hydroxide solution and applying to said oxidized layer a counterelectrode composed of bismuth.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Ceramic Engineering (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)
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Description

Oct. 16, 1956 E. LE LOUP 2,766,508
BLOCKING LAYER FOR TITANIUM OXIDE RECTIFIER Filed May 22, 1952 Ih'vehtor: Theodore E. Le Loup, y" p? 4. 7%
His Attorney.
BLOCKING LAYERFOR TITANIUM OXIDE RECTIFIER Theodore E. Le Loup, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application May 22, 1952, Serial No. 289,248
8 Claims. (Cl. 29-253) Thisinve'ntion relates toa titanium dioxideal ternating current rectifier; more particularly, it refers to a titanium dioxide rectifier having a blocking layer applied-by electrolytic anodization.
In the copending application of Le Loup and Marinace, SerialNo. 289,247, filed May 22, 1952, which is assigned to the same assignee as the present invention, a titanium dioxide rectifier is described together with a method for producing such a rectifier. In accordance with this copending application, a titanium rectifier is produced by heat treating a titanium plate in an atmosphere containing oxygen to produce an oxide layer, further treating the titanium plate to partially reduce the oxide layer, and applying over the partially reduced oxide layer a counterelectrode composed of a metal having a high work function.
It is an object of this invention to provide a titanium dioxide rectifier having a titanium dioxide blocking layer which confers improved rectification characteristics upon the rectifier.
It is another object of this invention to provide a method whereby a uniform blocking layer'may be incorporated in a titanium dioxide rectifier.
Briefly stated, in accordance with one embodiment'of this invention, a titanium plate is subjected to a heat treatment' in an oxidizing, or partially oxidizing, atmosphere to produce an oxide layer over at least a portion of the titanium plate surface. The partially oxidized layer is then subjected to an electrolytic anodization treat ment to provide a thin uniform blocking layer of oxide to which an overlying layer of counterelectrode metal having a high work function is then applied.
The drawing is a sectional view illustrating one embodiment of my invention. A base electrode 10 is composed of a titanium plate thick enough to impart rigidity to the device. Overlying all or a part of the titanium plate 10 is a'partially oxidized layer 11. Theexposed surface of the layer 11 is subjected to an electrolytic anodization treatment which results in the formation of a thin layer 12 of oxide. Overlyingall or a portion of the layer 12 is a counterelectrode layer 13 composed of a metal having a high work function. Y
The thickness of the layers 11, 12 and 13 is greatly exaggerated for purposes of clarity of illustration. The layers 11 and 12 are normally less than a thousandth of an inch in thickness and the layer 13 may be of the order of a thousandth of an inch. The base electrode 10 may be much thinner than it is shown in the illustration.
In preparing a titanium dioxide rectifier in accordance with my invention, the titanium plate 10 must have a clean surface. This may be obtained by subjecting a plate to an abrasive process or by treatment in an acid solution. A satisfactory acid solution in which the plate may be immersed consists of 80% nitric acid and hydrofluoric acid.
The plate is then subjected to a heat treatment in an atmosphere containing oxygen. The high melting States Patent ,Ece
2. point of titanium enables this treatment to be carried out at an extremely'high temperature. However, above 800 C. the rate of oxidation becomes a-little difiicult to controldue to the fact that it takes place rather rapidly. Below 600 C. the rate of oxidation is quite slow necessitating prolonged treatment. I prefer to carry out the oxidation between 600 C. and 800 C., within which range the. time of treatment varies from about two to five hours. However, it must be emphasized that there is nothing critical about the temperature and time of treatment. If the treatment temperaure is above 800 C., for example 1200" C., the time of treatment may be of the order of a few minutes. If the treatment temperature is below 600 C., for example 300 C., the time of treatment is many hours or. even ays.
Air and steam are both satisfactory oxidizing atmos. pheres but of? the two steam is preferable. Itis necessary that the layer 11 contain some reduced titanium dispersed therethrough. Consequently if the layer 11 is provided by an air oxidation treatment, there must also be a heat treatment in a. reducing atmosphere, such as hydrogen, to providethe free titanium necessary for rectificationaction. This may be provided by a heat treatment at the same temperature as the oxidation treatment in an atmosphere of hydrogen.
If. the oxygen containing atmosphere is provided by steam,,reducing action is provided by the hydrogen produced-in the decomposition of the water vapormolecule. For each atom of oxidizing oxygen, two atoms of reducing hydrogen are produced. Thus the steam treatment producesa layer 11. having-minute particles of titanium dispersed therethrough. The layer 11 should preferably have-a thickness of the'orderof 0.0005".
While the base electrode 10 is shown with the layer 11 coveringa portion of one surface thereof, in practice the layer. 11 covers the entire surface of the titanium base 10 since it is most easily manufactured with this construction.
After the reduction step the layer 11' is subjectedto an electrolytic anodization in order to provide a block-v ing layer. of oxide. It is well known that an oxide layer applied by electrolytic anodization is self-insulating. Thus, after the oxide layer on a particular portion of the layer 11 hasbeen built up to a particular thickness, no more current will flow through this portion and further oxidation, if any, will takeplace only on portions of the surface having a thinner oxide layer. This action re sul'tsin. an. oxide layer of uniform thickness over the entire surface.
Anodizing solutions are well known in the electrolytic art. Solutions of sodium hydroxide, potassium hydroxide, chromic: acid, ammonium hydroxide, and sul-. furic acid are all satisfactory for purposes of. applying an oxide blocking layer to the partially oxidized layer 11. I have obtained best results from the use of a sodium hydroxide solution of about 10 to 17 percent concentration. The base electrode 10 is made the anode in such a solution. The current density is a function of time (at constant voltage) and the back voltage of the cell is dependent on the final current density. The anodization is preferably accomplished by gradually increasing the potential to about 40 volts while keeping the current at about 5 ma./cm. Under continued application of 40 volts, the current decreases to a range of 5-20 ma. on a plate 1" x The anodization may be carried out with the solution at room temperature.
. After the anodization step has been completed, the counterelectrode 13 is applied by any method which will insure the close union of the layers 12 and 13. The
I method of effecting a close union between the layers 12 and 13 is dependent to some extent upon the nature of the counterelectrode metal used. Certain metals may be applied in a molten state while others are best applied by vapor deposition. In general, vapor deposition is a preferred method of applying the layer 13.
It has been previously mentioned that the counterelectrode 13 is composed of a metal having a high work function. Bismuth, nickel, and platinum fulfill these requirements whereas cadmium, zinc, tin, aluminum, and magnesium when used as counterelectrodes, produce a rectifier which is considerably inferior to a rectifier having a counterelectrode composed of bismuth, nickel, or
platinum. A possible explanation for this behavior lies in the fact that the partially oxidized titanium is an 11 type semi-conductor with the free titanium contributing the electron conduction. The counterelectrodes of bismuth, nickel, or platinum all have missing electrons in their d shells which contribute holes for a p conduction. The other metals mentioned do not have missing electrons in their d shells. used herein, the term high work function includes metals having missing electrons in their at shells which contribute holes for p type conduction.
The deposition of the counterelectrode on the n type titanium establishes a p-n junction. When the plates are anodized after a partial oxidation, there is a thin insulating layer, or a layer with fewer n or p carriers between the n type region and the p type region. This layer reduces the leakage and raises the reverse voltage of the rectifiers.
Of the satisfactory counterelectrodes previously enumerated, I prefer to use bismuth as this element has a low melting point which makes it easy to handle and a thin layer of bismuth allows the plate 10 to are through at a weak spot without destroying the rectifying properties of the device. A rectifier made in accordance with my invention has superior high temperature stability and compares favorably with other rectifiers from the standpoint of current loading and voltage rating.
While the present invention has been described with reference to particular embodiments thereof, it will be understood that numerous modifications may be made by those skilled in the art without actually departing from the invention. Therefore, I aim in the appended claims to cover all such equivalent variations as come within the true spirit and scope of the foregoing disclosure.
What I claim as new and desire to secure by Letters Patent of the United States is:
l. The method of preparing a titanium dioxide rectifier which comprises forming a partially oxidized layer on a surface of a titanium plate by heating said plate in an atmosphere containing oxygen, forming a layer of oxide on said partially oxidized surface by electrolytic anodization and applying to said oxide layer a counterelectrode metal having a high work function.
2. The method of preparing a titanium dioxide rectifier which comprises forming a partially oxidized layer on a surface of a titanium plate by heating said plate Accordingly, as
type
in a steam atmosphere, forming an oxidized layer on said partially oxidized layer by electrolytic anodization and applying to said oxidized layer a counterelectrode metal having a high work function.
3. The method of preparing a titanium dioxide rectifier which comprises forming a partially oxidized layer on a surface of a titanium plate by heating said plate to a temperature in excess of 600 C. in an atmosphere of steam for four hours, forming an oxidized layer on said partially oxidized layer by electrolytic anodization and applying to said oxidized layer a counterelectrode metal having a high work function.
4. The method of preparing a titanium dioxide rectifier which comprises forming a partially oxidized layer on a surface of a titanium plate by heating said plate in an atmosphere containing oxygen, forming an oxidized layer on said partially oxidized layer by electrolytic anodization in an aqueous sodium hydroxide bath and applying to said oxidized layer a counterelectrode metal having a high work function.
5. The method of claim 4 wherein the concentration of the sodium hydroxide solution is between 10% and 17% and the anodization is carried out at room temperature.
6. The method of preparing a titanium dioxide rectifier which comprises forming a partially oxidized layer on a titanium plate by heating said plate in an atmosphere containing oxygen, forming an oxidized layer on said partially oxidized layer by electrolytic anodization in a chromic acid solution and applying to said oxidized layer a counterelectrode metal having a high work function.
7. The method of preparing a titanium dioxide rectifier which comprises forming a partially oxidized layer on the surface of a titanium plate by heating said plate in an atmosphere containing oxygen, forming an oxidized layer on said partially oxidized layer by electrolytic anodization in an ammonium hydroxide solution and applying to said oxidized layer a counterelectrode metal having a high work function.
8. The method of preparing a titanium dioxide rectifier which comprises forming a partially oxidized layer on a surface of a titanium plate by heating said plate to a temperature between 600 C. and 700 C. in an atmosphere of steam for about four hours, forming an oxidized layer on said partially oxidized layer by electrolytic anodization in sodium hydroxide solution and applying to said oxidized layer a counterelectrode composed of bismuth.
References Cited in the file of this patent UNITED STATES PATENTS 1,968,571 Rupp '-s- July 31, 1934 1,985,118 Van Geel et al Dec. 18, 1934 2,291,592 Dowling July 28, 1942 2,692,212 Jenkins et al Oct. 19, 1954 2,695,380 Mayer et al. Nov. 23, 1954

Claims (1)

1. THE METHOD OF PREPARING A TITANIUM DIOXIDE RECTIFIER WHICH COMPRISES FORMING A PARTIALLY OXIDIZED LAYER ON A SURFACE OF A TITANIUM PLATE BY HEATING SAID PLATE IN AN ATMOSPHERE CONTAINING OXYGEN, FORMING A LAYER OF OXIDE ON SAID PARTIALLY OXIDIZED SURFACE BY ELECTROLYTIC ANODIZATION AND APPLYING TO SAID OXIDE LAYER A COUNTERELECTRODE METAL HAVING A HIGH WORK FUNCTION.
US289248A 1952-05-22 1952-05-22 Blocking layer for titanium oxide rectifier Expired - Lifetime US2766508A (en)

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US289248A US2766508A (en) 1952-05-22 1952-05-22 Blocking layer for titanium oxide rectifier
US289247A US2766509A (en) 1952-05-22 1952-05-22 Titanium dioxide rectifier
GB13888/53A GB736251A (en) 1952-05-22 1953-05-18 Improvements in and relating to titanium oxide rectifiers
GB13887/53A GB733267A (en) 1952-05-22 1953-05-18 Improvements in and relating to titanium dioxide rectifiers
BE520122D BE520122A (en) 1952-05-22 1953-05-21
FR1083556D FR1083556A (en) 1952-05-22 1953-05-22 New titanium dioxide straightener

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US289248A US2766508A (en) 1952-05-22 1952-05-22 Blocking layer for titanium oxide rectifier
US289247A US2766509A (en) 1952-05-22 1952-05-22 Titanium dioxide rectifier

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US3264707A (en) * 1963-12-30 1966-08-09 Rca Corp Method of fabricating semiconductor devices
US3337429A (en) * 1964-05-28 1967-08-22 Union Carbide Corp Solid electrolytic capacitor and process therefor

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US2940941A (en) * 1953-05-26 1960-06-14 R daltqn
US2826725A (en) * 1953-11-10 1958-03-11 Sarkes Tarzian P-n junction rectifier
US2942134A (en) * 1955-03-16 1960-06-21 Bendix Aviat Corp Gap bridging material
NL246765A (en) * 1958-12-23
US2978618A (en) * 1959-04-13 1961-04-04 Thomas E Myers Semiconductor devices and method of making the same
US3139754A (en) * 1961-06-15 1964-07-07 Sylvania Electric Prod Electronic vacuum gauge
US3310685A (en) * 1963-05-03 1967-03-21 Gtc Kk Narrow band emitter devices
US3391309A (en) * 1963-07-15 1968-07-02 Melpar Inc Solid state cathode
DE1266353B (en) * 1964-03-13 1968-04-18 Bbc Brown Boveri & Cie Matrix-shaped arrangement of oxide layer diodes for use as manipulable read-only memory or information converter
US3502953A (en) * 1968-01-03 1970-03-24 Corning Glass Works Solid state current controlled diode with a negative resistance characteristic
US4385966A (en) * 1980-10-07 1983-05-31 Bell Telephone Laboratories, Incorporated Fabrication of thin film resistors and capacitors
US4361951A (en) * 1981-04-22 1982-12-07 Ford Motor Company Method of fabricating a titanium dioxide rectifier
US4394672A (en) * 1981-04-22 1983-07-19 Ford Motor Company Titanium dioxide rectifier

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US1968571A (en) * 1931-10-14 1934-07-31 Gen Electric Electric current rectifier
US1985118A (en) * 1930-03-08 1934-12-18 Philips Nv Dry rectifier
US2291592A (en) * 1940-08-10 1942-07-28 Union Switch & Signal Co Electrical rectifier
US2692212A (en) * 1950-02-09 1954-10-19 Westinghouse Brake & Signal Manufacture of dry surface contact rectifiers
US2695380A (en) * 1949-08-26 1954-11-23 Int Standard Electric Corp Electric current rectifier

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GB483088A (en) * 1936-10-13 1938-04-12 Franz Rother Improvements in and relating to barrier plane rectifying cells and photo-electric cells
US2721966A (en) * 1950-06-22 1955-10-25 Westinghouse Brake & Signal Manufacture of dry surface contact rectifiers

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Publication number Priority date Publication date Assignee Title
US1985118A (en) * 1930-03-08 1934-12-18 Philips Nv Dry rectifier
US1968571A (en) * 1931-10-14 1934-07-31 Gen Electric Electric current rectifier
US2291592A (en) * 1940-08-10 1942-07-28 Union Switch & Signal Co Electrical rectifier
US2695380A (en) * 1949-08-26 1954-11-23 Int Standard Electric Corp Electric current rectifier
US2692212A (en) * 1950-02-09 1954-10-19 Westinghouse Brake & Signal Manufacture of dry surface contact rectifiers

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3264707A (en) * 1963-12-30 1966-08-09 Rca Corp Method of fabricating semiconductor devices
US3337429A (en) * 1964-05-28 1967-08-22 Union Carbide Corp Solid electrolytic capacitor and process therefor

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BE520122A (en) 1955-05-27
GB736251A (en) 1955-09-07
FR1083556A (en) 1955-01-11
US2766509A (en) 1956-10-16
GB733267A (en) 1955-07-06

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