US2613301A - Process of manufacturing photoelectric cells - Google Patents

Process of manufacturing photoelectric cells Download PDF

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US2613301A
US2613301A US137301A US13730150A US2613301A US 2613301 A US2613301 A US 2613301A US 137301 A US137301 A US 137301A US 13730150 A US13730150 A US 13730150A US 2613301 A US2613301 A US 2613301A
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semi
conductor
layer
base plate
selenium
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US137301A
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Dubar Leon Jules Marie Joseph
Millet Roger Philippe
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Compagnie des Freins et Signaux Westinghouse SA
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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
    • H01L21/108—Provision of discrete insulating layers, i.e. non-genetic barrier layers
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • 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
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12528—Semiconductor component
    • 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
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12535—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.] with additional, spatially distinct nonmetal component
    • Y10T428/12611—Oxide-containing component
    • 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
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771—Transition metal-base component
    • Y10T428/12861—Group VIII or IB metal-base component
    • Y10T428/12868—Group IB metal-base component alternative to platinum group metal-base component [e.g., precious metal, etc.]

Definitions

  • a barrier layer photo-electric cell consists, like a dry rectifier, of a thin layer of a semi-conductor. interposed between two metallic electrodes.
  • the base plate serves as a mechanical support Afor the semi-conductor, with which as perfect as possible an electrical connection is made.
  • the phenomena of asymmetric conductivity are localized at the contact of the semi-conductor and the second electrode, called the counterelectrode. It ,i is agreed that this asymmetry is due to the existence, at the interface between the metal of the counterelectrode and the semi-conductor, of ⁇ a very thin layer of high resistivity, called the bar-v rierlayer, which isfformed in the course of the manufacturing treatment.
  • the photo-electric cell differs from the rectifier in that the counterelectrode, consisting, for
  • the cell constitutes a rectifier, .it will be -seen that the photo-electric current which flows :from the negative pole to ⁇ the positivej pole ⁇ through the cell, that is to say, fromthe counter- Yelectrode to the base plate, ilows in the high resistance direction through the rectifier.
  • the present invention due to the Work of Messrs. ⁇ Roger Millet and ⁇ Lon Dubar, obtains cells.- of delinitely increased electromotive force by reduction of the leakage currents of which the origin will be explained thus:
  • This result is obtained according to the invention by creating a barrier layer between the semi-conductor and the base plate.
  • a second rectfying contact is obtained, in opposition to the rectifying contact of the semi-conductor and counterelectrode.
  • This back contact allows however the useful photo-electric current to pass easily and notably reduces the leakage currents in the reverse direction.
  • it eiciently blocks the photoelectrons, strongly retarded by their passage through the semi-conductor. which are emitted directly toward the-'base plate.
  • the'use- may be indicated of a base plate of a metal capable ⁇ oi forming with the selenium a non-conducting compound.
  • This metal can be, for example, cadmium, zinc, aluminum, antimony, etc. use'das a solid plate or an electrolytic deposit.
  • the 'barrier layer is formed by association of the selenium with the metal after the heat treatment which transforms the selenium to a conducting variety. The duration and the temperature. of this heat treatment can be regulated to obtain the optimum properties at the same time for the selenium and the barrier layer, the other treatments remaining unchanged.
  • theA example of realization given is not limited bythe invention but may be applied to any barrier-layer cell whether it is of selenium or not and, nally, that the secondbarrier layer. between the semi-conductor and the base plate or back layer can be realized in any known manner.
  • the invention by no meansv depends upon the theoretical considerations disclosed above. servation of the increase in the difference 4of potential on open vcircuit by means of strong illumination following the creation of a rectifying contact between the base plate and the semiconductor and not to the explanations which may be given for this result.
  • the' useful photo-electric current is not sensibly affected while the undesired leakage currents are notably attenuated.
  • the result is an increase in the internal resistance and in the electromotive force of the cell permitting the latter to deliver a larger power to a receiver.
  • Fig.V 1l is la plan view
  • Fig. 2 is a cross-section View of a photoelectric cell constructed according 'to our invention
  • Fig. 3 is a view showing an enlarged portion of the cross-section view shown in Fig. 2.
  • a base plate 2 is provided, of a metal which can be, for example, cadmium, zinc, aluminum, antimony, etc., used It rests uniquely upon the actual obeither as a solid plate, or an electrolytic deposit on a supporting base plate l, A layer 3 of a semi-conductor selenium material is then applied to the exposed or upper side of base plate 2, as shown in the drawing.
  • a heat treatment in an oven at a temperature above centigrade but not exceeding the melting point of selenium, the layer 3 of semi-conductor selenium material becomes transformed into a conducting Variety.
  • a counterelectrode consisting, for example, of a thin layer 4 of gold or platinum, is applied to the exposed side of selenium layer 3, and a suitable collector electrode, such for example as a ring shaped electrode 5 may be applied to counterelectrode 4.
  • barrier layer 6 is shown between selenium layer 3 and counterelectrode 4.
  • Asecond barrier layer 1 is also formed between the base plate 2 and layer 3 of selenium. Barrier layer 1 has higher resistance to the flow of current. inI the direction from base plate 2 to selenium layer 3 than in the opposite direction from selenium layer 3 to base plate 2, whereas barrier layer 6, as is Well known, has higher resistance to the ilow of current in the direction from counterelectrode ylv to selenium layer 3, than from layer 3 tofcounterelectrode 4.
  • a process of manufacturing a photo-electric cell which comprises depositing an organic film suchas varnish, or aiilm of a mineral selected.
  • said-.layer of ysemi-conductor material Eimplying heat to transform said semi-conductor material into a conducting state, in which said barrier layer is formed between said base plate and said layer of semi-conductor material, said barrier layer having high resistance to electric current of agiven ⁇ polarity and having low resistance tol electric current of the opposite polarity, and in which La second barrier layer is formed betweenr said thin layer of metal and said opposite side of said'A layer of semi-conductor material, said ⁇ second barrier layer having low resist-ance to' ⁇ electric current of said given polarity, andhaving high resistance to electric current of. said opposite polarity.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biotechnology (AREA)
  • Electromagnetism (AREA)
  • Light Receiving Elements (AREA)

Description

Oct. 7, 1952 J. M. J. DUBAR ETAL 2,613,301
PROCESS OF MANUFACTURING PHOTOELECTRIC CELLS Filed Jan. 6, 1950 Selena/12.9, f A? 4 /ola 017 Pla'nzmz.
/ezppl'ef' Jaya? 'aamlmz, op Zinc, op HIM/22mm, 0P412122012y,
IN VEN TORS e012 Jules MgJ 5650/1: @ahw /Ue M5566.
and Hagel Piz Patented Oct. 7, 19h52 PROCESS F MANUFACTURING PHOTOELECTRIC CELLS Lon Jules Marie Joseph Dubar, Paris, and Roger Philippe Millet, "Pavillons-'sous-Bois, France, assignors to Compagnie des Freins et Signaux Westinghouse, Paris, France Application January 6, 195.0,fSeriai No. 137,301'` In FrancehJanuai-y 17, 1949 A barrier layer photo-electric cell consists, like a dry rectifier, of a thin layer of a semi-conductor. interposed between two metallic electrodes. In the rectifiers one of the electrodes, the base plate, serves as a mechanical support Afor the semi-conductor, with which as perfect as possible an electrical connection is made. The phenomena of asymmetric conductivity are localized at the contact of the semi-conductor and the second electrode, called the counterelectrode. It ,i is agreed that this asymmetry is due to the existence, at the interface between the metal of the counterelectrode and the semi-conductor, of` a very thin layer of high resistivity, called the bar-v rierlayer, which isfformed in the course of the manufacturing treatment.
trons in the direction from the metal to the semi-conductor, than -in the reverse direction. In consequence, the direction of the lgreater conductivitycorrespon'ds to theflow of current `from the base plate to the counterelectrode` through the semi-conductor. A
The photo-electric cell differs from the rectifier in that the counterelectrode, consisting, for
example, of a thin layer y,of gold or platinum, allows light to pass while'lrhaining conductive. If the surface-of the semi-conductor is illuminated through the counterelectrode, the appearance of an electrical difference of potential may be observed between it andthe baseplate; the positive pole being the base plate.` Thisdif-I ference of potential on open 'circuit is not'proportional to the illumination but increases lessrapidly and appearsto tend toward a saturation'v `is sensibly proportional to the illumination. :Since the cell constitutes a rectifier, .it will be -seen that the photo-electric current which flows :from the negative pole to `the positivej pole `through the cell, that is to say, fromthe counter- Yelectrode to the base plate, ilows in the high resistance direction through the rectifier.
These phenomena may beexplained, as for the rectifier, by the existence of a barrier layer between the semi-conductor and the counterelectrode. The light, traversing the latter, liberates some electrons in the' semi-conductor. Those which have suiicient energy traverse the barrier On This layer istraversed much more easily by the conducting 'elec- 2 equilibrium is established between the electrons passing from the semi-conductor to the counterelectrodel and those which recombine with their ions in taking the reverse path, and a sort of saturation intervenes. On short circuit, on the contrary, this manifestation practically does not appear, the current forcing the electrons to move all together and they recombine with their ions after having entered the exterior path including the load circuitl and the base'plate. Under these conditions, the current delivered is proportional to the number of electrons liberated per second inthe semi-conductor by the primary photoelectric e'ect. Y 'Y It will be seen'that on the one hand the useful photo-electric current traverses the barrier` layer inthe direction corresponding to the blocking resistance of the contact between the semi-conductor and the counterelectrode; on the other hand the currents of direct recombination of electrons with l their positive ions take the reverse path, which is that of the low resistance of the contact.` However, in addition to this recombination, which hasv its location vin a space very close to the barrier layer, there exists some leakage'currents which are not negligible which flow directly from the counterelectrode to the base plate perhaps clue to defects in the surface, or through the non-illuminatedportions of the cell (collector ring, for example). Finally, certain 'photo-electrons, which, moreover, are more numerous when the illumination is very intense, iiow directly from the semi-conductor to the base plate. In effect, the semi-conductor is not rigorously opaque and the region of emission of photoelectrons approaches closer to the base plate 4 when the illumination is very intense.
These different defects contribute each in part to the diminution of the potential difference on open circuit with strong illumination. Now it is evident that the power capable of being furnished by the. cell to a load device will moreover be greater, for the same short circuit current, if the difference of potential of the cell on open circuit,
whichL may be likened to an apparent electrometive force,` is increased, under the condition that theapparent resistance of the load apparatus is adapted to the apparent internal resistance of thecell.
The present invention, due to the Work of Messrs. `Roger Millet and `Lon Dubar, obtains cells.- of delinitely increased electromotive force by reduction of the leakage currents of which the origin will be explained thus: This result is obtained according to the invention by creating a barrier layer between the semi-conductor and the base plate. Thus a second rectfying contact is obtained, in opposition to the rectifying contact of the semi-conductor and counterelectrode. This back contact allows however the useful photo-electric current to pass easily and notably reduces the leakage currents in the reverse direction. Moreover, it eiciently blocks the photoelectrons, strongly retarded by their passage through the semi-conductor. which are emitted directly toward the-'base plate.
By way of example, and not as a limitation, as applied to the selenium cell, the'use-may be indicated of a base plate of a metal capable `oi forming with the selenium a non-conducting compound. This metal can be, for example, cadmium, zinc, aluminum, antimony, etc. use'das a solid plate or an electrolytic deposit. The 'barrier layer is formed by association of the selenium with the metal after the heat treatment which transforms the selenium to a conducting variety. The duration and the temperature. of this heat treatment can be regulated to obtain the optimum properties at the same time for the selenium and the barrier layer, the other treatments remaining unchanged.
Experience has shown that besides a notable increase in the difference of .potential on open circuit, which can reach up to 0.5 volt at 1.200 lux, there is obtained with certainy metals such as cadmium a remarkable adherence of the layer of selenium to the base plate sufficient to enable optionally the. omission ofthe usual roughening of the base plate by a sand blast. This property should likewise be considered as one of th results accomplishedb'y the invention.
It is obvious that theA example of realization given is not limited bythe invention but may be applied to any barrier-layer cell whether it is of selenium or not and, nally, that the secondbarrier layer. between the semi-conductor and the base plate or back layer can be realized in any known manner. Thisconsi'sts of a deposit on the base plate, previous tothe addition thereto of the semi-conductor, of an appropriate insulating film, organic (such as varnish) or mineral (such as quartz.. fluorite, cryolite, the deposit being made by evaporation in vacuum).
Moreover, the invention by no meansv depends upon the theoretical considerations disclosed above. servation of the increase in the difference 4of potential on open vcircuit by means of strong illumination following the creation of a rectifying contact between the base plate and the semiconductor and not to the explanations which may be given for this result.
By reason of the present invention, having regard to the direction of recticati'on, the' useful photo-electric current is not sensibly affected while the undesired leakage currents are notably attenuated. The result is an increase in the internal resistance and in the electromotive force of the cell permitting the latter to deliver a larger power to a receiver. 'Y
In the accompanying drawing, Fig.V 1l is la plan view, and Fig. 2 is a cross-section View of a photoelectric cell constructed according 'to our invention; and Fig. 3 is a view showing an enlarged portion of the cross-section view shown in Fig. 2.
Referring to the drawing, a base plate 2 is provided, of a metal which can be, for example, cadmium, zinc, aluminum, antimony, etc., used It rests uniquely upon the actual obeither as a solid plate, or an electrolytic deposit on a supporting base plate l, A layer 3 of a semi-conductor selenium material is then applied to the exposed or upper side of base plate 2, as shown in the drawing. By means of a heat treatment, in an oven at a temperature above centigrade but not exceeding the melting point of selenium, the layer 3 of semi-conductor selenium material becomes transformed into a conducting Variety.
A counterelectrode consisting, for example, of a thin layer 4 of gold or platinum, is applied to the exposed side of selenium layer 3, and a suitable collector electrode, such for example as a ring shaped electrode 5 may be applied to counterelectrode 4.
In Fig. 3, the usual barrier layer 6 is shown between selenium layer 3 and counterelectrode 4. Asecond barrier layer 1 is also formed between the base plate 2 and layer 3 of selenium. Barrier layer 1 has higher resistance to the flow of current. inI the direction from base plate 2 to selenium layer 3 than in the opposite direction from selenium layer 3 to base plate 2, whereas barrier layer 6, as is Well known, has higher resistance to the ilow of current in the direction from counterelectrode ylv to selenium layer 3, than from layer 3 tofcounterelectrode 4.
Having thus describedour invention, what we claim is:
A process of manufacturing a photo-electric cell which comprises depositing an organic film suchas varnish, or aiilm of a mineral selected.
from the'gro-up consisting. of quartz, uorite and v cryolite 'ony afbase plate of a metal capable of forming a barrier layer with eterni-conductor material such asl selenium, then depositing a layer of said semi-conductor material on said lm, providing av thin layer of metal such as gold or` platinuml in contact with the opposite side/of. said-.layer of ysemi-conductor material, Eimplying heat to transform said semi-conductor material into a conducting state, in which said barrier layer is formed between said base plate and said layer of semi-conductor material, said barrier layer having high resistance to electric current of agiven `polarity and having low resistance tol electric current of the opposite polarity, and in which La second barrier layer is formed betweenr said thin layer of metal and said opposite side of said'A layer of semi-conductor material, said` second barrier layer having low resist-ance to'` electric current of said given polarity, andhaving high resistance to electric current of. said opposite polarity.
LEONJULES MARIE JOSEPH DUBAR. ROGER. PHILIPPE MILLET.
REFERENCESCITED AThe following references are of record in the l'e' vof this 'patenti t UNITED STATES PATENTS
US137301A 1949-01-17 1950-01-06 Process of manufacturing photoelectric cells Expired - Lifetime US2613301A (en)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2804580A (en) * 1953-08-13 1957-08-27 Visseaux S A J Unidirectionally conducting elements
US2853663A (en) * 1954-07-08 1958-09-23 Vickers Inc Power transmission
US2901348A (en) * 1953-03-17 1959-08-25 Haloid Xerox Inc Radiation sensitive photoconductive member
US2979402A (en) * 1956-07-31 1961-04-11 Rca Corp Electrostatic printing
US3599060A (en) * 1968-11-25 1971-08-10 Gen Electric A multilayer metal contact for semiconductor device
US4094675A (en) * 1973-07-23 1978-06-13 Licentia Patent-Verwaltungs-G.M.B.H. Vapor deposition of photoconductive selenium onto a metallic substrate having a molten metal coating as bonding layer
US4139857A (en) * 1975-07-18 1979-02-13 Futaba Denshi Kogyo Kabushiki Kaisha Schottky barrier type solid-state element

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US420884A (en) * 1890-02-04 mercadier
US1827016A (en) * 1927-07-02 1931-10-13 Ind Res Company Photoelectric cell
GB500094A (en) * 1937-06-05 1939-02-02 British Thomson Houston Co Ltd Improvements in and relating to dry rectifiers and photo-electric cells
US2476042A (en) * 1946-12-26 1949-07-12 Gen Electric Selenium rectifier and process of fabrication

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US420884A (en) * 1890-02-04 mercadier
US1827016A (en) * 1927-07-02 1931-10-13 Ind Res Company Photoelectric cell
GB500094A (en) * 1937-06-05 1939-02-02 British Thomson Houston Co Ltd Improvements in and relating to dry rectifiers and photo-electric cells
US2476042A (en) * 1946-12-26 1949-07-12 Gen Electric Selenium rectifier and process of fabrication

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2901348A (en) * 1953-03-17 1959-08-25 Haloid Xerox Inc Radiation sensitive photoconductive member
US2804580A (en) * 1953-08-13 1957-08-27 Visseaux S A J Unidirectionally conducting elements
US2853663A (en) * 1954-07-08 1958-09-23 Vickers Inc Power transmission
US2979402A (en) * 1956-07-31 1961-04-11 Rca Corp Electrostatic printing
US3599060A (en) * 1968-11-25 1971-08-10 Gen Electric A multilayer metal contact for semiconductor device
US4094675A (en) * 1973-07-23 1978-06-13 Licentia Patent-Verwaltungs-G.M.B.H. Vapor deposition of photoconductive selenium onto a metallic substrate having a molten metal coating as bonding layer
US4139857A (en) * 1975-07-18 1979-02-13 Futaba Denshi Kogyo Kabushiki Kaisha Schottky barrier type solid-state element

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GB658503A (en) 1951-10-10

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