US3816787A - Photoconductor comprising cadmium selenide - Google Patents

Photoconductor comprising cadmium selenide Download PDF

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Publication number
US3816787A
US3816787A US00172541A US17254171A US3816787A US 3816787 A US3816787 A US 3816787A US 00172541 A US00172541 A US 00172541A US 17254171 A US17254171 A US 17254171A US 3816787 A US3816787 A US 3816787A
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United States
Prior art keywords
layer
cadmium
selenide
target
photoelectric
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Expired - Lifetime
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US00172541A
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English (en)
Inventor
K Shimizu
O Yoshida
K Terakawa
S Aihara
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Toshiba Corp
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Tokyo Shibaura Electric Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
    • H01J29/36—Photoelectric screens; Charge-storage screens
    • H01J29/39—Charge-storage screens
    • H01J29/45—Charge-storage screens exhibiting internal electric effects caused by electromagnetic radiation, e.g. photoconductive screen, photodielectric screen, photovoltaic screen
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/20—Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel
    • H01J9/233—Manufacture of photoelectric screens or charge-storage screens

Definitions

  • the photoelectric conductor device comprises a first layer of cadmium selenide or cadmium sulfoselenide, a second layer formed on the first layer and made of a substance containing cadmium salt of oxy-acid, and a third layer formed on the second layer, the third layer being made of a high resistance substance having a resistivity of more than 10 ohm-cm and being selected from the group of compounds not including cadmium selenide.
  • an object of this invention is to provide an improved photoelectric conductor device having small dark current and which does not vary appreciably with time.
  • Another object of this invention is to provide a method of manufacturing such an improved photoelectric conductor device having low dark current and especially suitable for use as a photoelectric target of an image pickup tube.
  • a photoelectric conductor device comprising a first layer made of a photoelectric conductive substance containing cadmium selenide, a second layer formed on the first layer and made of a substance containing cadmium salt of oxy-acid, and a third layer formed on the second layer and made of a high resistance compound other than cadmium selenide, said high resistance compound having a resistivity of more than 10 ohm-cm.
  • a method of manufacturing a photoelectric conductor device comprising the steps of vapour depositing a layer of cadmium selenide upon a transparent electroconductive film formed on a face plate under a pressure of from 1 mmHg to 2 X 10 mm Hg; heat treating the layer of cadmium selenide in an inert gas atmosphere for a predetermined time, and then heat treating the layer of cadmium selenide in selenium vapour for a predetermined time; subjecting the layer of cadmium selenide to a heat treatment at a predetermined temperature and then to a quenching treatment in an inert gas atmosphere containing oxygen and selenium vapour whereby to form a layer of cadmium salt of selenious acid; and depositing a layer of a predetermined thickness of a high resistance compound other than cadmium selenide upon the cadmium salt of selenious acid, said high resistance compound having a resistivity of more than ohm-
  • FIG. 1 shows a crosssection of a photoelectric target embodying the invention and utilized in an image pickup tube
  • FIG. 2 show a plot of an X-ray diffraction pattern of the photoelectric target shown in FIG. 1;
  • FIG. 3 is a graph comparing thetarget voltage viz, current characteristics of the photoelectric target and of a prior art target
  • FIG. 4 is a graph comparing the target voltage viz, dark current characteristics of the photoelectric target shown in FIG. 1 and of the prior art target;
  • FIG. 5 is a plot comparing the time viz, dark current characteristics of the photoelectric target shown in FIG. 1 and of the prior art target.
  • FIGS. 6 and 7 show modified targets to be used in an image pickup tube of the solid state scanning type.
  • a transparent electroconductive signal electrode for example, an N ESA coating 2 is applied onto the inner surface of a transparent glass face plate 1, that is the light receiving surface of an evacuated photoelectric conductor type image pickup tube, a vidicon for example.
  • a first photoelectric conductor layer 3 of cadmium selenide is applied onto the NESA coating 2 to a thickness of about 2 microns.
  • Cadmium selenide may be substituted by a solid solution containing cadmium selenide and cadmium sulfide at a weight ratio of 2 I or by cadmium sulfoselenide.
  • the intermediate layer 4 is coated with a third layer 5 of a high resistance compound other than cadmium selenide and having a high resistivity of more than about 10 ohm-cm, for example zinc sulfide, thus completing a photoelectric target 6.
  • the intermediate layer 4 may be formed of a mixture of cadmium salt of selenious acid and cadmium oxide instead of a pure cadmium salt of selenious acid.
  • zinc sulfide constituting the third layer 5 may be substituted by a high resistance compound having a resistivity of more than about 10 ohm-cm and selected from the group consisting of germanium sulfide, arsenic disulfide, arsenic trisulfide, arsenic triselenide, germanium selenide, thallium sulfide, thallium selenide, bismuth trisulfide, bismuth triselenide, zinc selenide, cadmium telluride, antimony trisulfide and antimony triselenide.
  • the third layer 5 was shown as comprising a single high resistance compound it may be a mixture of two or more high resistance compounds described above or may comprise a multi-layer construction of a single or a mixture of these compounds.
  • One example of the method of manufacturing the target 6 is as follows:
  • face plate 1 is coated with a transparent electroconductive film, for example an NESA coating 2, by the well known vacuum deposition technique.
  • the coated face plate is then put into a vacuum of from 1 mmHg to 2 X 10 mm Hg and a layer 3 of cadmium selenide is deposited upon the NESA coating to a thickness of about 2 microns, for example.
  • cadmium selenide may be incorporated with one or more of copper, gold, silver, indium, gallium, aluminium, halogens, tellurium, antimony, bismuth, lead, tin, alkali metals, alkali earth metals and thallium.
  • high purity cadmium selenide of say 99.999 percent may be deposited.
  • the face plate 1 formed with layer 3 in this manner is heat treated for about 15 minutes at a temperature of 600C in an inert gas, for example in nitrogen atmosphere.
  • the face plate is then heat treated for 30 minutes at a temperature of 500C, for example in a vapour of selenium.
  • the purpose of the heat treatment of the cadmium selenide layer 3 in the vapour of selenium is to supply a plurality of deficiences of the selenium in cadmium selenide. in this manner the photoelectric conductor layer 3 of cadmium selenide of high photosensitivity is formed.
  • the face plate 1 with photoelectric conductor layer 3 formed in this manner is then heated in an inert gas for example nitrogen atmosphere containing oxygen and maintained at a normal pressure, the inert gas containing selenium vapour of the quantity exhibiting a partial pressure of from 1 mm Hg, for example to the partial pressure of the saturated vapour pressure at a predetermined temperature.
  • the heat treated face plate is then cooled rapidly.
  • a second layer 4 of cadmium salt of selenious acid is formed on the first layer 3.
  • a third layer of zinc sulfide is vacuum deposited upon the second layer 4 to a thickness of about 0.1 micron, for example, under a vacuum of mm Hg, thus completing a composite target 6.
  • the heat treatments for the first and second layers were performed independently, these heat treatments may be combined into a single step.
  • cadmium selenide layer 3 is deposited onto transparent conductive coating 2 formed on the face plate 1 until a thickness of about 2 microns is reached in an inert gas for example nitrogen atmosphere.
  • face plate 1 is maintained at a temperature of about 150C.
  • the resulting first layer 3 is then heat treated for 10 to 50 minutes at a temperature of 500C in nitrogen atmosphere under normal pressure and containing 0.1 to 10 percent of oxygen.
  • the nitrogen atmosphere is incorporated with selenium vapour of the quantity exhibiting a partial pressure of from 1 mm Hg to the partial pressure of the saturated vapour pressure of the atmosphere at a predetermined temperature.
  • the oxygen in the selenium vapour is effective to decrease the grain size distribution of the fine particles of cadmium selenide in layer 3, thus producing cadmium selenide layer 3 having a substantially uniform grain size.
  • the composition of the atmosphere is adjusted during the cooling step of the target following the heat treatment such that the quantity of oxygen and the partial pressure of the selenium vapour in the treating atmosphere are reduced to zero after a suitable time.
  • the second layer 4 of cadmium salt of selenious acid is formed on the first layer 3.
  • the second layer 4 may be formed by heating at a temperature of 300C, for example, the cadmium selenide layer 3 together with selenium dioxide.
  • Third layer 5 of arsenic trisulfide is deposited onto the second layer 4 to a thickness of 0.4 micron under a reduced pressure of 10' mm Hg, thus completing composite target 6.
  • a thin layer of the monocrystal of cadmium selenide having a suitable electrical resistance and photosensitivity may be bonded upon NESA coating 2.
  • the intermediate layer 4 may be made of a mixture of this cadmium salt and cadmium oxide or a mixture of the cadmium salt of selenious acid and an intermediate compound of cadmium, selenium and oxygen expressed by a molecular formula Cd Se O,,(3CdSeO SeO for example.
  • Cd Se O,,(3CdSeO SeO a molecular formula
  • the percentage of cadmium oxide should not be too high.
  • too thick layer of cadmium salt of selenious acid causes a positive after image on the television display screen, thus resulting in the persistence of the image after interruption of the light input. For this reason, a thickness of less than about 2,000A is preferred.
  • the presence of the layer 4 of cadmium salt of selenious acid or a mixture thereof with cadmium oxide which is formed on the cadmium selenide layer can be affirmed by verifying the result of X-ray diffraction test with the ASTM cards.
  • FlG. 2 shows one example of a portion of such an X-ray diffraction pattern of the photoelectric conductor target which was obtained by using X-rays of CuKa, a type of X-rays in which large peaks of the diffraction show the presence of the hexagonal system of the cadmium selenide in the first layer.
  • FIG. 3 is a plot to compare the target voltage viz, signal current characteristic of the photoelectric target 6 with a prior art target, in which a solid line curve shows the characteristic of the target whereas a dotted line curve that of the prior art target.
  • the light input to the target was white light as 2,850K and the brightness at the light receiving surface of the target was 0.5 lux.
  • both characteristics are generally similar except that the target operates at a target voltage of few volts higher and that the gamma value of light transfer characteristic of the target is about 0.9, a slight improvement over 0.85 of the conventional design.
  • the target Under a suitable operating voltage, like the prior art target, the target can also pro Jerusalem a signal current of more than 200nA under a brightness of 0.5 lux which shows that the photosensitivity of the photoelectric conductor device is also excellent.
  • the plot depicted in FIG. 4 compares the target voltage viz, dark current characteristics of the photoelectric target 6 and the prior art target in which a solid line curve shows the characteristic of the target whereas a dotted line that of the prior art target.
  • a preferred target voltage 40 volts for example, according to the invention it is possible to reduce the dark current to less than lnA and can more effectively suppress the increase in the dark current than the prior target when the target voltage is increased.
  • FlG. 5 is a plot to compare the dark current characteristics with time of the target and the prior art target. Although the dark current of the prior art target increases rapidly with time as shown by a dotted line, that of the target does not vary appreciably with time as shown by a solid horizontal line.
  • the photoelectric conductor device has a small dark current which is maintained nearly constant over an extended period of use so that when applied to the photoelectric conductor target of an image pickup tube it is possible to greatly improve the signal-to-noise ratio of the television camera, thus improving the operational stability thereof.
  • third layer 5 is scanned by an electron beam emitted by an electron gun, not shown, to produce from signal electrode 2 a video signal corresponding to the incident light.
  • FlG. 6 shows a solid state type photoelectric conductor target 6 including a plurality of spaced apart parallel strip electrodes 7 on the outer surface of the third layer 5.
  • a potential is applied successively to strip electrodes 7 for producing video signals at signal electrode 2.
  • signal electrode is divided into a plurality of discrete strip signal electrodes 2a.
  • This embodiment has better resolution than that shown in FIG. 6.
  • a photoelectric conductor device comprising a transparent electroconductive film, a first layer formed on said film consisting of photoelectric conductive material selected from the group consisting of cadmium selenide, a mixture of cadmium selenide and cadmium sulfide at a weight ratio of 2: l and cadmium sulfoselenide, a second layer capable of reducing dark current of the device formed on said first layer, said second layer consiwting of material selected from the group consisting of cadmium selenite and a mixture of cadmium selenite and cadmium oxide and having a thickness of less than 2,000A and a third layer formed on said second layer of high resistance compound having a resistivity of more than l0 ohm-cm selected from the group consisting of zinc sulfide, germanium sulfide, arsenic disulfide, arsenic trisulfide, arsenic triselenide, germanium seleni
  • a photoelectric conductor device comprising a transparent electroconductive film, a first layer made of photoelectric conductive material consisting of cadmium selenide, a second layer having a thickness less than 2,000A consisting of cadmium selenite and a third layer formed on said second layer made of a high resistance compound having a resistivity of more than 10 ohm-cm selected from the group consisting of zinc sulfide, germanium sulfide, arsenic disulfide, arsenic trisulfide, arsenic triselenide, germanium selenide, thallium sulfide, thallium selenide, bismuth trisulfide, bismuth triselenide, zinc selenide, cadmium telluride, antimony trisulfide, antimony triselenide and mixtures thereof.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
  • Light Receiving Elements (AREA)
  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
US00172541A 1970-08-17 1971-08-17 Photoconductor comprising cadmium selenide Expired - Lifetime US3816787A (en)

Applications Claiming Priority (1)

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JP45071392A JPS4830193B1 (enrdf_load_stackoverflow) 1970-08-17 1970-08-17

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US3816787A true US3816787A (en) 1974-06-11

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US (1) US3816787A (enrdf_load_stackoverflow)
JP (1) JPS4830193B1 (enrdf_load_stackoverflow)
CA (1) CA922421A (enrdf_load_stackoverflow)
DE (1) DE2141233B2 (enrdf_load_stackoverflow)
FR (1) FR2112921A1 (enrdf_load_stackoverflow)
GB (1) GB1311404A (enrdf_load_stackoverflow)
NL (1) NL161613C (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3947717A (en) * 1975-03-31 1976-03-30 Rca Corporation Photoconductor of cadmium selenide and aluminum oxide
US4088485A (en) * 1973-12-07 1978-05-09 Xerox Corporation Graded bandgap xerographic plate
DE3917139A1 (de) * 1988-05-27 1989-11-30 Hitachi Ltd Verfahren zur herstellung einer bildaufnahmeroehre und eines darin verwendeten speicherplattensegments
CN119029054A (zh) * 2024-10-24 2024-11-26 正泰新能科技股份有限公司 一种边缘钝化的晶硅电池与钙钛矿晶硅叠层电池及制备

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2213580B1 (enrdf_load_stackoverflow) * 1972-10-12 1977-09-09 Matsushita Electric Ind Co Ltd
JPS58147414U (ja) * 1982-03-29 1983-10-04 チロン・ジヤパン株式会社 装身具
RU2273074C1 (ru) * 2004-07-20 2006-03-27 ОАО "Центральный научно-исследовательский институт "Электрон" Мишень видикона

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2843773A (en) * 1955-08-17 1958-07-15 Emi Ltd Pick-up tube targets
US2843772A (en) * 1953-03-25 1958-07-15 Rca Corp Cathode ray tube and target
US3346755A (en) * 1966-03-31 1967-10-10 Rca Corp Dark current reduction in photoconductive target by barrier junction between opposite conductivity type materials
US3486059A (en) * 1966-01-11 1969-12-23 Tokyo Shibaura Electric Co High sensitivity photoconductor for image pickup tube
GB1198570A (en) * 1967-07-17 1970-07-15 Tokyo Shibaura Electric Co A Photoconductive Target.

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2843772A (en) * 1953-03-25 1958-07-15 Rca Corp Cathode ray tube and target
US2843773A (en) * 1955-08-17 1958-07-15 Emi Ltd Pick-up tube targets
US3486059A (en) * 1966-01-11 1969-12-23 Tokyo Shibaura Electric Co High sensitivity photoconductor for image pickup tube
US3346755A (en) * 1966-03-31 1967-10-10 Rca Corp Dark current reduction in photoconductive target by barrier junction between opposite conductivity type materials
GB1198570A (en) * 1967-07-17 1970-07-15 Tokyo Shibaura Electric Co A Photoconductive Target.

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4088485A (en) * 1973-12-07 1978-05-09 Xerox Corporation Graded bandgap xerographic plate
US3947717A (en) * 1975-03-31 1976-03-30 Rca Corporation Photoconductor of cadmium selenide and aluminum oxide
DE3917139A1 (de) * 1988-05-27 1989-11-30 Hitachi Ltd Verfahren zur herstellung einer bildaufnahmeroehre und eines darin verwendeten speicherplattensegments
CN119029054A (zh) * 2024-10-24 2024-11-26 正泰新能科技股份有限公司 一种边缘钝化的晶硅电池与钙钛矿晶硅叠层电池及制备

Also Published As

Publication number Publication date
NL7111347A (enrdf_load_stackoverflow) 1972-02-21
FR2112921A1 (enrdf_load_stackoverflow) 1972-06-23
DE2141233A1 (de) 1972-02-24
NL161613B (nl) 1979-09-17
JPS4830193B1 (enrdf_load_stackoverflow) 1973-09-18
DE2141233B2 (de) 1973-09-20
CA922421A (en) 1973-03-06
NL161613C (nl) 1980-02-15
GB1311404A (en) 1973-03-28

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