US2745047A - Selenium rectifiers and method of manufacture - Google Patents

Selenium rectifiers and method of manufacture Download PDF

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US2745047A
US2745047A US261726A US26172651A US2745047A US 2745047 A US2745047 A US 2745047A US 261726 A US261726 A US 261726A US 26172651 A US26172651 A US 26172651A US 2745047 A US2745047 A US 2745047A
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selenium
layer
nickel
electrode
rectifier
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Paul E Lighty
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TDK Micronas GmbH
International Telephone and Telegraph Corp
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Deutsche ITT Industries GmbH
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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
    • H01L21/06—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 comprising selenium or tellurium in uncombined form other than as impurities in semiconductor bodies of other materials
    • H01L21/10—Preliminary treatment of the selenium or tellurium, its application to the foundation plate, or the subsequent treatment of the combination
    • 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
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02367—Substrates
    • H01L21/0237—Materials
    • H01L21/02425—Conductive materials, e.g. metallic silicides
    • 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
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02436—Intermediate layers between substrates and deposited layers
    • H01L21/02439—Materials
    • H01L21/02491—Conductive materials
    • 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
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02518—Deposited layers
    • H01L21/02521—Materials
    • 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
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02612—Formation types
    • H01L21/02617—Deposition types
    • 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
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02656—Special treatments
    • H01L21/02664—Aftertreatments
    • H01L21/02667—Crystallisation or recrystallisation of non-monocrystalline semiconductor materials, e.g. regrowth
    • 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
    • H01L21/06—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 comprising selenium or tellurium in uncombined form other than as impurities in semiconductor bodies of other materials
    • H01L21/08—Preparation of the foundation plate
    • 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
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S73/00—Measuring and testing
    • Y10S73/05—Liquid levels with magnetic transmission

Definitions

  • This invention relates to electrical rectifiers and more particularly to selenium rectifiers and methods of manufacturing same.
  • the blocking voltage of a rectifier is defined as that A. C. voltage which may be applied to the rectifier without exceeding the maximum permissible reverse current, and the maximum permissible reverse current is determined by the permissible power dissipation, which is in turn dictated by the highest temperature which the rectifier will withstand without deterioration.
  • One of the objects of this invention is to produce selenium rectifiers having improved blocking voltage and forward conductivity characteristics which are measurably better than obtained by manufacturing processes heretofore practiced.
  • Another object is to provide an improved method of producing selenium rectifiers wherein not only the blocking voltage and forward conductivity are greatly increased but improved selenium adherence to the base electrode is also obtained.
  • Still another object is to provide a more eificient rectifier than obtained heretofore; and a further object is to provide such a rectifier utilizing less selenium than required by manufacturing processes heretofore practiced.
  • One of the features of the invention is the manner in which greatly increased blocking voltage and forward conductivity are obtained.
  • the selenium layer is found to be inter-laced with many fine cracks. It is believed that these cracks in the selenium layer may contribute to incipient short circuits or weak spots which must be burnt out before or during electroforining.
  • the present invention eliminates such cracks by applying a first selenium layer to a nickel surfaced electrode which is then heated to an elevated 2,745,047 Patented May 8,, 1956 ICC temperature sufiicient to form a layer of nickel selenide of the interface portions of the nickel surface and the layer of selenium.
  • This compound of nickel selenide is formed in situ by subjecting the electrode to a temperature of at least 400 C., the resulting nickel selenide providing a consistent and intimate bond between the selenium and the electrode surface. This improved bond also renders less critical the toughening operation of the base electrode heretofore believed necessary for adher ence of the selenium layer.
  • the nickel selenide layer by eliminating substantially the presence of cracks or weak spots and by providing an intimate interface bond, makes for higher forward conductivity and higher blocking voltages. Rectifiers containing this nickel selenide layer also show indications of having good aging and long useful life characteristics.
  • a base electrode 1 is shown surfaced at least on one side thereof with a layer of nickel 2.
  • the base electrode may comprise any suitable conductor, such as iron, aluminum, magnesium, beryllium and various alloys thereof.
  • the surface 3 of the base electrode is preferably roughened by sand blasting or by chemical etching. While this toughening has proved in prior practice to be a critical operation for insuring proper adherence of the selenium layer, it is found not to be critical when the method for improving adherence of selenium is practiced according to the present invention.
  • the nickel surfacing may be applied to the roughened surface by known plating techniques, such as described in the paper entitled Some Chemical and Physical Problems in the Manufacture of Selenium Rectifiers by C. A. Escoffery, Transactions of the Electrochemical Society, vol. 90, 1946, pages 129-162.
  • the next operation is the application of a first layer of selenium 4 to the nickel surface 2.
  • This thin layer or film of selenium may be applied by any one of a number of methods.
  • the selenium may be applied by heating the electrode to a temperature above the melting point of selenium and applying the selenium by rubbing a stick of the material across the surface or by placing it in powder or pellet form on the heated surface.
  • Another method of application is to spread selenium in the pellet or powder form over the electrode and then to simultaneously press and heat the selenium to effect an adherent layer.
  • Still another method may involve vaporization of the selenium to produce a selenium film on the nickel surface.
  • the coating maybe obtained by dipping the electrode in a bath of selenium maintained slightly above the melting temperature of selenium. While material, usually selected from the halogen group, is added to the selenium to improve its rectifying characteristics, it is not necessary in the present invention to add such materials to the first application of selenium. Regardless of whether one of the methods referred to above or some 3 perature of 400 C. or higher.
  • This heating operation may be carried out in any one of a number of different ways. For example, a flame may be applied to either the coated or uncoated side of the electrode, the electrode may be placed on a hot plate, or the electrode may be placed within an oven or furnace. It is found important in this operation that the electrode be heated to a temperature of at least 400 C.
  • This heating operation should be of a duration, depending on the maximum temperature used, sufficient to thin out the selenium until the entire nickel surface has a continuous wetted appearance without the pres ence of bubbles.
  • the temperature employed may exceed considerably the lower limit of 400 C., the higher the temperature the shorter the heating interval.
  • the duration of heating is not critical, but where the temperature exceeds 500 C. the heating interval must be shortened to avoid excess evaporation of the selenium.
  • T he formation of the nickel selenide in situ insures an intimate bond between the selenium and the nickel surface of the electrode. This compound being of a metallic character and intimately bonded to the electrode does not have the fine cracks that have been observed in selenium layers made by other processes.
  • this surplus may be removed by spinning the electrode during the high temperature treatment. It is found, however, that where the pressed powder method is employed, such spinning is unneces sary providing the selenium is reduced to a finely divided state suflicient to pass a 200 mesh screen. It is found however that spinning is desirable to remove excessive selenium during the high temperature treatment when the particles are of the '80 mesh screen size.
  • a second coating of amorphous selenium is applied. Any suitable method may be used, reference being made to the examples above mentioned. I have found, however, that if selenium of the 200 mesh size is used rather than the coarse material conventionally employed, a saving in the amount of selenium can be made. In actual practice of the present invention using 200 mesh particles, savings up to 30% can be achieved.
  • This second coating 6 of selenium may include other material, in the order of a fraction of one percent, to improve the rectifying characteristics of the final product, one such class of materials being the halides of selenium such as the mono-chloride, mono-bromide or monoiodide.
  • one such class of materials being the halides of selenium such as the mono-chloride, mono-bromide or monoiodide.
  • the next operation is the known annealing operation wherein the electrodes, coated as described above, are subjected to a heat treatment of from 215 C. to 220 C. for about 15 to 35 minutes during which the amorphous selenium is converted to the crystalline state as indicated at 7. Substantially all of the selenium contained in layer 6 and possibly also some of the selenium of layer 4 bonded to the nickel selenide stratum is converted to the crystalline state.
  • the selenium surface is coated with a barrier layer or film 8 usually applied in lacquer form.
  • This barrier layer may be applied by any one of a number of methods proposed in the prior art, but the preferred method is believed to be the application of a lacquer such as disclosed in U. S. Patent No. 2,386,750, dated October 16, 1945, assigned to Federal Telephone and Radio Corporation.
  • a counter-electrode material 9 is applied, such as for example, a cadmium-bismuth-eutectic alloy.
  • the device thus produced is next subjected to an electroforming operation as hereinbefore stated to develop the final blocking voltage and forward conductivity characteristics of the rectifier.
  • the blocking voltages of the rectifiers made in accordance with the present invention have ranged from about 36 volts to as high :as volts. For consistent production, blocking voltages in the lower portion of this range are assured. It is believed, however, that consistent high blocking voltages of the order of 60 volts can be obtained by close control of the operating steps herein outlined.
  • the increased forward conductivity of the rectifier over rectifiers made by methods heretofore practiced is found to be from 30 to 40%, thus resulting in greatly improved efliciency.
  • the step comprising producing a layer of .a compound of nickel selenide at the interface portions of the layers of nickel and selenium by heating said two layers to an elevated temperature of at least 400 C.
  • said elevated temperature is between about 400 C. and 500 C.
  • the steps comprising applying a layer of selenium to an electrode having a nickel surface, producing a layer of a compound of nickel selenide on said electrode by heating the selenium coated electrode to an elevated temperature of at least 400 C. and spinning the electrode during the production of nickel selenide to thereby remove surplus selenium.
  • a selenium rectifier comprising applying a layer of selenium to an electrode having a nickel surface, said selenium being in a finely divided state in the order of 200 mesh size, and producing a layer of a compound of nickel selen-ide on said electrode by heating the electrode to an elevated temperature of at least 400 C.
  • a selenium rectifier comprising applying a first layer of selenium to an electrode having a nickel surface, heating the selenium coated electrode to an elevated temperature to produce a compound of nickel selenide of the interface portions of the nickel and selenium, applying a second layer of amorphous selenium on said first layer, and annealing the electrode thus coated to convert the selenium layer to a crystalline state.
  • a selenium rectifier comprising applying a first layer of amorphous selenium to a nickel coated electrode, heating the selenium coated electrode to an elevated temperature to produce a compound of nickel selenide of the interface portions of the nickel and selenium, applying a second layer of amorphous selenium on said first layer, annealing the electrode thus'coated to convert the selenium to a crystalline state, applying a barrier layer to the selenium and coating over the barrier layer with a layer of counter-electrode material.
  • a rectifier comprising an electrode having a nickel surface, a layer of selenium and a layer of a compound of nickel selenide interposed between said surface and said layer of selenium.
  • a rectifier comprising an electrode having a nickel surface, a layer of selenium and a layer of a compound of nickel selenide formed in situ firom the interface portions of said nickel and said selenium.
  • a rectifier comprising an electrode having a nickel surface, a layer of selenium, a layer of nickel selenide bonding intimately the interface portions of said nickel surface and said layer of selenium, a barrier layer dis- 5 posed on said selenium and a counter-electrode layer disposed on said barrier layer.

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Description

May 8, 1956 P. E UGHTY 2,745,047
SELENIUM RECTIFIERS AND METHOD OF MANUFACTURE Filed Dec. 14, 1951 NICKEL SURF/ICED EL EC TRODE V NICKEL 2 \\\\\\w 5,455 METAL/ 5 COATED WITH F/RST LAYER 0F SELE/VIUM SELEN/UM 4 \XX HEAT TREATMENT OF 400%.,
0/? HIGHERJO FORM N/CKEL-SEL EN/DE NICKEL SEL EN/DE5 fg if A SEL ENIUM 6 SELEN/UM CRYSTALS FORMED BY HEAT TREATMENT 7 Ulllllllllll COATED WITH A BARE/El? LAYER BARR/ER LAYER8- H WW7 COATED WITH A COUNTER- ELECTRODE COUNTER- ELECTRODE 9- mm 8 5 7 INVENTOR ATTO RN EY United States Patent O SELENIUM RECTIFIERS AND METHOD OF MANUFACTURE Paul E. Lighty, Lafayette, N. 1., assignor to International Telephone and Telegraph Corporation, a corporation of Maryland Application December 14, 1951, Serial No. 261,726
12 Claims. (Cl. 317-441) This invention relates to electrical rectifiers and more particularly to selenium rectifiers and methods of manufacturing same.
In the manufacture of selenium rectifiers, it is the practice heretofore to first thoroughly roughen a base elec trode to obtain selenium adherence, either by sand blasting or chemical etching, to nickel plate the roughened'surface, apply a layer of amorphous selenium, heat treat the selenium coated electrode for a period of time sufficient to convert the selenium to a crystalline state, apply a barrier or blocking film to the selenium and apply thereto a counter-electrode. The rectifier thus produced is electroformed by subjecting it to an electric current in the reverse direction to develop the blocking voltage and forward conductivity characteristics of the rectifier.
The blocking voltage of a rectifier is defined as that A. C. voltage which may be applied to the rectifier without exceeding the maximum permissible reverse current, and the maximum permissible reverse current is determined by the permissible power dissipation, which is in turn dictated by the highest temperature which the rectifier will withstand without deterioration.
Considerable effort has been made heretofore to increase this blocking voltage without increasing the reverse current beyond a permissible maximum. While some improvement has been made over the past few years by variation of ingredients and variation in the process steps employed, the best consistent blocking voltage obtainable heretofore was in the neighborhood of about 26 volts per cell. Any further improvement in such blocking voltage characteristic carried with it a decrease of forward conductivity and useful rectifier life.
One of the objects of this invention is to produce selenium rectifiers having improved blocking voltage and forward conductivity characteristics which are measurably better than obtained by manufacturing processes heretofore practiced.
Another object is to provide an improved method of producing selenium rectifiers wherein not only the blocking voltage and forward conductivity are greatly increased but improved selenium adherence to the base electrode is also obtained.
Still another object is to provide a more eificient rectifier than obtained heretofore; and a further object is to provide such a rectifier utilizing less selenium than required by manufacturing processes heretofore practiced.
One of the features of the invention is the manner in which greatly increased blocking voltage and forward conductivity are obtained. in the manufacture of selenium rectifiers, as heretofore practiced, particularly where the pressed powder method of applying amorphous selenium is used, the selenium layer is found to be inter-laced with many fine cracks. It is believed that these cracks in the selenium layer may contribute to incipient short circuits or weak spots which must be burnt out before or during electroforining. The present invention eliminates such cracks by applying a first selenium layer to a nickel surfaced electrode which is then heated to an elevated 2,745,047 Patented May 8,, 1956 ICC temperature sufiicient to form a layer of nickel selenide of the interface portions of the nickel surface and the layer of selenium. This compound of nickel selenide is formed in situ by subjecting the electrode to a temperature of at least 400 C., the resulting nickel selenide providing a consistent and intimate bond between the selenium and the electrode surface. This improved bond also renders less critical the toughening operation of the base electrode heretofore believed necessary for adher ence of the selenium layer. The nickel selenide layer, by eliminating substantially the presence of cracks or weak spots and by providing an intimate interface bond, makes for higher forward conductivity and higher blocking voltages. Rectifiers containing this nickel selenide layer also show indications of having good aging and long useful life characteristics.
The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent by reference to the following de scription of an embodiment taken in conjunction with the accompanying drawing, wherein the sole figure is a diagrammatical illustration of a flow chart showing specimens, in exaggerated proportions for illustration purposes, at different stages in the process of manufacturing a selenium rectifier.
In the drawing a base electrode 1 is shown surfaced at least on one side thereof with a layer of nickel 2. The base electrode may comprise any suitable conductor, such as iron, aluminum, magnesium, beryllium and various alloys thereof. The surface 3 of the base electrode is preferably roughened by sand blasting or by chemical etching. While this toughening has proved in prior practice to be a critical operation for insuring proper adherence of the selenium layer, it is found not to be critical when the method for improving adherence of selenium is practiced according to the present invention. The nickel surfacing may be applied to the roughened surface by known plating techniques, such as described in the paper entitled Some Chemical and Physical Problems in the Manufacture of Selenium Rectifiers by C. A. Escoffery, Transactions of the Electrochemical Society, vol. 90, 1946, pages 129-162.
The next operation, according to the present invention, is the application of a first layer of selenium 4 to the nickel surface 2. This thin layer or film of selenium may be applied by any one of a number of methods. For example, the selenium may be applied by heating the electrode to a temperature above the melting point of selenium and applying the selenium by rubbing a stick of the material across the surface or by placing it in powder or pellet form on the heated surface. Another method of application is to spread selenium in the pellet or powder form over the electrode and then to simultaneously press and heat the selenium to effect an adherent layer. Still another method may involve vaporization of the selenium to produce a selenium film on the nickel surface. Further, the coating maybe obtained by dipping the electrode in a bath of selenium maintained slightly above the melting temperature of selenium. While material, usually selected from the halogen group, is added to the selenium to improve its rectifying characteristics, it is not necessary in the present invention to add such materials to the first application of selenium. Regardless of whether one of the methods referred to above or some 3 perature of 400 C. or higher. This heating operation may be carried out in any one of a number of different ways. For example, a flame may be applied to either the coated or uncoated side of the electrode, the electrode may be placed on a hot plate, or the electrode may be placed within an oven or furnace. It is found important in this operation that the electrode be heated to a temperature of at least 400 C. in order to insure formation of a layer of a compound of nickel selenide 5 at the interface portions of the nickel surface and the selenium layer. This heating operation should be of a duration, depending on the maximum temperature used, sufficient to thin out the selenium until the entire nickel surface has a continuous wetted appearance without the pres ence of bubbles. The temperature employed may exceed considerably the lower limit of 400 C., the higher the temperature the shorter the heating interval. For temperatures ranging between 400 and 500 C., the duration of heating is not critical, but where the temperature exceeds 500 C. the heating interval must be shortened to avoid excess evaporation of the selenium. T he formation of the nickel selenide in situ insures an intimate bond between the selenium and the nickel surface of the electrode. This compound being of a metallic character and intimately bonded to the electrode does not have the fine cracks that have been observed in selenium layers made by other processes.
Where a surplus of selenium is applied during the first application of selenium, this surplus may be removed by spinning the electrode during the high temperature treatment. It is found, however, that where the pressed powder method is employed, such spinning is unneces sary providing the selenium is reduced to a finely divided state suflicient to pass a 200 mesh screen. It is found however that spinning is desirable to remove excessive selenium during the high temperature treatment when the particles are of the '80 mesh screen size.
Following the high temperature treatment, a second coating of amorphous selenium is applied. Any suitable method may be used, reference being made to the examples above mentioned. I have found, however, that if selenium of the 200 mesh size is used rather than the coarse material conventionally employed, a saving in the amount of selenium can be made. In actual practice of the present invention using 200 mesh particles, savings up to 30% can be achieved.
This second coating 6 of selenium may include other material, in the order of a fraction of one percent, to improve the rectifying characteristics of the final product, one such class of materials being the halides of selenium such as the mono-chloride, mono-bromide or monoiodide. The reason why such addition material need not be included in the first selenium layer is that the high heat treatment would undoubtedly drive off the addition agent, and furthermore, such addition agent is not essential to the formation of the adherent nickel selenide strata 5.
The next operation is the known annealing operation wherein the electrodes, coated as described above, are subjected to a heat treatment of from 215 C. to 220 C. for about 15 to 35 minutes during which the amorphous selenium is converted to the crystalline state as indicated at 7. Substantially all of the selenium contained in layer 6 and possibly also some of the selenium of layer 4 bonded to the nickel selenide stratum is converted to the crystalline state.
After conversion of the amorphous selenium to the crystalline state, the selenium surface is coated with a barrier layer or film 8 usually applied in lacquer form. This barrier layer may be applied by any one of a number of methods proposed in the prior art, but the preferred method is believed to be the application of a lacquer such as disclosed in U. S. Patent No. 2,386,750, dated October 16, 1945, assigned to Federal Telephone and Radio Corporation. Following application of the barrier layer, a counter-electrode material 9 is applied, such as for example, a cadmium-bismuth-eutectic alloy.
The device thus produced is next subjected to an electroforming operation as hereinbefore stated to develop the final blocking voltage and forward conductivity characteristics of the rectifier. The blocking voltages of the rectifiers made in accordance with the present invention have ranged from about 36 volts to as high :as volts. For consistent production, blocking voltages in the lower portion of this range are assured. It is believed, however, that consistent high blocking voltages of the order of 60 volts can be obtained by close control of the operating steps herein outlined. The increased forward conductivity of the rectifier over rectifiers made by methods heretofore practiced is found to be from 30 to 40%, thus resulting in greatly improved efliciency. By practicing the present invention, it is found that a saving can be made of selenium through the formation of thinner selenium layers, and due to the higher efficiency of the cells, a smaller number of cells are required for a given stack voltage.
While I have described above the principles of my invention in connection with specific apparatus and method steps, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of my invention, as set forth in the objects thereof and in the accompanying claims.
I claim:
1. In the method of making a selenium rectifier containing adjacent layers of nickel and selenium, the step comprising producing a layer of .a compound of nickel selenide at the interface portions of the layers of nickel and selenium by heating said two layers to an elevated temperature of at least 400 C.
2. In the method according to claim 1, wherein said elevated temperature is between about 400 C. and 500 C.
3. In the method of making a selenium rectifier, the steps comprising applying a layer of selenium to an electrode having a nickel surface, producing a layer of a compound of nickel selenide on said electrode by heating the selenium coated electrode to an elevated temperature of at least 400 C. and spinning the electrode during the production of nickel selenide to thereby remove surplus selenium.
4. In the method of making a selenium rectifier, the steps comprising applying a layer of selenium to an electrode having a nickel surface, said selenium being in a finely divided state in the order of 200 mesh size, and producing a layer of a compound of nickel selen-ide on said electrode by heating the electrode to an elevated temperature of at least 400 C.
5. In the method of making a selenium rectifier, the steps comprising applying a first layer of selenium to an electrode having a nickel surface, heating the selenium coated electrode to an elevated temperature to produce a compound of nickel selenide of the interface portions of the nickel and selenium, applying a second layer of amorphous selenium on said first layer, and annealing the electrode thus coated to convert the selenium layer to a crystalline state.
6. In the method according to claim 5, wherein the step of heating of the first layer of selenium is brought to an elevated temperature of at least 400 C.
7. In the method according to claim 5, wherein the selenium for said second layer is selected in a finely divided state of the order of 200 mesh size.
8. In the method according to claim 5, wherein the selenium for both said firs-t and said second layers is selected in a finely divided state of the order of 200 mesh size.
9. In the method of making a selenium rectifier, the steps comprising applying a first layer of amorphous selenium to a nickel coated electrode, heating the selenium coated electrode to an elevated temperature to produce a compound of nickel selenide of the interface portions of the nickel and selenium, applying a second layer of amorphous selenium on said first layer, annealing the electrode thus'coated to convert the selenium to a crystalline state, applying a barrier layer to the selenium and coating over the barrier layer with a layer of counter-electrode material.
10. A rectifier comprising an electrode having a nickel surface, a layer of selenium and a layer of a compound of nickel selenide interposed between said surface and said layer of selenium.
11. A rectifier comprising an electrode having a nickel surface, a layer of selenium and a layer of a compound of nickel selenide formed in situ firom the interface portions of said nickel and said selenium.
12. A rectifier comprising an electrode having a nickel surface, a layer of selenium, a layer of nickel selenide bonding intimately the interface portions of said nickel surface and said layer of selenium, a barrier layer dis- 5 posed on said selenium and a counter-electrode layer disposed on said barrier layer.
References Cited in the file of this patent UNITED STATES PATENTS 10 2,433,353 Escofiery Dec. 30, 1947 2,446,237 Mueller Aug. 3,1948 2,504,226 R-au et a1. Apr. 18, 1950 2,524,270 'Pelfrey Oct. 3, 1950 2,644,915 Thurber et a1. July 7, 1953

Claims (1)

1. IN THE METHOD OF MAKING A SELENIUM RECTIFIER CONTAINING ADJACENT LAYERS OF NICKEL AND SELENIUM, THE STEP COMPRISING PRODUCING A LAYER OF A COMPOUND OF NICKEL SELENIDE AT THE INTERFACE PORTIONS OF THE LAYERS OF NICKEL AND SELENIUM BY HEATING SAID TWO LAYERS TO AN ELEVATED TEMPERATURE OF AT LEAST 400* C.
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2994621A (en) * 1956-03-29 1961-08-01 Baldwin Piano Co Semi-conductive films and methods of producing them
US3052572A (en) * 1959-09-21 1962-09-04 Mc Graw Edison Co Selenium rectifiers and their method of manufacture
US3187414A (en) * 1959-02-05 1965-06-08 Baldwin Co D H Method of producing a photocell assembly
DE1229192B (en) * 1956-10-11 1966-11-24 Standard Elektrik Lorenz Ag Process for the manufacture of selenium rectifiers
US3297921A (en) * 1965-04-15 1967-01-10 Int Rectifier Corp Controlled rectifier having shunted emitter formed by a nickel layer underneath an aluminum layer
US3694908A (en) * 1969-04-25 1972-10-03 Siemens Ag Method of producing a selenium rectifier
CN109273355A (en) * 2018-06-06 2019-01-25 鹤壁维达科巽电气有限公司 A kind of selenium cell preparation process

Citations (5)

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Publication number Priority date Publication date Assignee Title
US2433353A (en) * 1946-03-13 1947-12-30 Standard Telephones Cables Ltd Method of roughening the surface of ferrous elements
US2446237A (en) * 1944-11-11 1948-08-03 Fansteel Metallurgical Corp Selenium rectifier
US2504226A (en) * 1948-07-28 1950-04-18 Vickers Inc Devices which have selenium as constituent parts thereof
US2524270A (en) * 1945-09-27 1950-10-03 Sylvania Electric Prod Selenium rectifier
US2644915A (en) * 1950-07-24 1953-07-07 Bell Telephone Labor Inc Selenium rectifier and method of its production

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2446237A (en) * 1944-11-11 1948-08-03 Fansteel Metallurgical Corp Selenium rectifier
US2524270A (en) * 1945-09-27 1950-10-03 Sylvania Electric Prod Selenium rectifier
US2433353A (en) * 1946-03-13 1947-12-30 Standard Telephones Cables Ltd Method of roughening the surface of ferrous elements
US2504226A (en) * 1948-07-28 1950-04-18 Vickers Inc Devices which have selenium as constituent parts thereof
US2644915A (en) * 1950-07-24 1953-07-07 Bell Telephone Labor Inc Selenium rectifier and method of its production

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2994621A (en) * 1956-03-29 1961-08-01 Baldwin Piano Co Semi-conductive films and methods of producing them
DE1229192B (en) * 1956-10-11 1966-11-24 Standard Elektrik Lorenz Ag Process for the manufacture of selenium rectifiers
US3187414A (en) * 1959-02-05 1965-06-08 Baldwin Co D H Method of producing a photocell assembly
US3052572A (en) * 1959-09-21 1962-09-04 Mc Graw Edison Co Selenium rectifiers and their method of manufacture
US3297921A (en) * 1965-04-15 1967-01-10 Int Rectifier Corp Controlled rectifier having shunted emitter formed by a nickel layer underneath an aluminum layer
US3694908A (en) * 1969-04-25 1972-10-03 Siemens Ag Method of producing a selenium rectifier
CN109273355A (en) * 2018-06-06 2019-01-25 鹤壁维达科巽电气有限公司 A kind of selenium cell preparation process
CN109273355B (en) * 2018-06-06 2022-03-01 鹤壁维达科巽电气有限公司 Preparation process of selenium rectifying sheet

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GB713929A (en) 1954-08-18

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