US3858955A - Method of making a iii-v compound electron-emissive cathode - Google Patents

Method of making a iii-v compound electron-emissive cathode Download PDF

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Publication number
US3858955A
US3858955A US323746A US32374673A US3858955A US 3858955 A US3858955 A US 3858955A US 323746 A US323746 A US 323746A US 32374673 A US32374673 A US 32374673A US 3858955 A US3858955 A US 3858955A
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United States
Prior art keywords
cesium
cathode
temperature
exposing
iii
Prior art date
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Expired - Lifetime
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US323746A
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English (en)
Inventor
Alfred Hermann Sommer
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RCA Corp
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RCA Corp
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Filing date
Publication date
Application filed by RCA Corp filed Critical RCA Corp
Priority to US323746A priority Critical patent/US3858955A/en
Priority to IT27369/73A priority patent/IT992789B/it
Priority to NL7313189A priority patent/NL7313189A/xx
Priority to SU7301958617A priority patent/SU568405A3/ru
Priority to SE7313657A priority patent/SE387773B/xx
Priority to DD173922A priority patent/DD107172A5/xx
Priority to DE19732350872 priority patent/DE2350872C3/de
Priority to AU61278/73A priority patent/AU482492B2/en
Priority to FR7336613A priority patent/FR2214169B1/fr
Priority to JP11525073A priority patent/JPS52668B2/ja
Priority to CA183,373A priority patent/CA993030A/en
Priority to GB5214173A priority patent/GB1453965A/en
Application granted granted Critical
Publication of US3858955A publication Critical patent/US3858955A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • H01J9/02—Manufacture of electrodes or electrode systems
    • H01J9/12—Manufacture of electrodes or electrode systems of photo-emissive cathodes; of secondary-emission electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J43/00—Secondary-emission tubes; Electron-multiplier tubes
    • H01J43/04—Electron multipliers
    • H01J43/06—Electrode arrangements
    • H01J43/18—Electrode arrangements using essentially more than one dynode
    • H01J43/20—Dynodes consisting of sheet material, e.g. plane, bent
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2201/00—Electrodes common to discharge tubes
    • H01J2201/32—Secondary emission electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2201/00—Electrodes common to discharge tubes
    • H01J2201/34—Photoemissive electrodes

Definitions

  • the buffer source provides the 2401734 6/1946 Jan g 316/5 X increasing and decreasing concentrations of cesium e.
  • the present invention relates to processing of electron-emissive tubes, particularly those in which the electron-emissive cathode is a III-V compound coated with a work-function-reducing layer comprising cesium.
  • cathode refers to any structure which emits electrons into vacuum.
  • Cathodes are used for example as photocathodes, dynodes, and electron gun cathodes in various electron-emissive tubes.
  • Semiconductor compounds of the elements aluminum, gallium, indium, phosphorus, arsenic, and antimony, chosen from Groups [II and V of the Periodic Chart of the Elements, are known to be particularly efficient cathodes for both primary and secondary electron emission. They are generally activated by being coated with a layer of cesium in combination with a strongly electronegative element, such as oxygen or fluorine. Examples ofsuch III-V compound cathodes, as well as activation techniques therefor, are described for instance, in the following US. Pat. Nos:
  • III-V compound cathodes are their instability in operation.
  • the bonding of cesium to the surface of the III-V compound crystal is relatively weak, as compared to the bonding of cesium to other, more conventional, photocathode base materials such as antimony.
  • III-V compounds are presently activated with cesium at temperatures below 100C.
  • a III-V photocathode activated by present techniques of activating III-V compound cathodes is subjected to temperatures above 100C, the work-function-reducing coating formed on the surface does not form as desired for a practical device.
  • Cathodes of III-V compounds activated at the lower temperatures according to prior art practices, on the other hand perform well initially, but become somewhat unstable, even when operated with relatively low current. After a time, their emission is seriously degraded by loss of cesium from the work-functionreducing layer.
  • the novel method of making a III-V compound cathode comprises exposing the cathode to cesium vapor at a temperature below 100C. Then the cathode temperature is raised to above about 100C, while the cathode is exposed to cesium vapor, until the emission is substantially constant. The cesium concentration to which the cathode is exposed is increased during the raising of the temperature to above about 100C and decreased during the lowering of the temperature therefrom.
  • the hovel tube comprises a cesilum buffer source inside the envelope.
  • the buffer source is a material incompletely reacted with cesium, and provides a small amount of cesium vapor in the interior of the tube envelope during the processing above 100C, to buffer the loss of cesium from the cathode at that tempera ture.
  • the novel tube with the cesium buffer source conveniently provides the appropriate low cesium pressure itself from the buffer sourceduring the processing above 100C.
  • the buffer source releases cesium at an increasing rate with a rising temperatureto increase the concentration and absorbs cesium at an increasing rate with a lowering temperature to decrease the concentration.
  • FIG. 1 shows a novel'photomultiiplier tube in accor- I PREFERRED EMBODIMENT OF THE INVENTION
  • a preferred'embodiment of the: novel tube is processed in accordance with a preferred embodiment of the novel method.
  • the novel tube is particularly suited for processing in accordance with the novel method. For convenience, the tube structure is described first.
  • the tube 10, shown in FIG. 1, is a photomultiplier tube having a glass-envelope l2 and a base 14 provided with a number of metal pins 16 for making electrical contact to internal components.
  • a metal shield 18 inside the envelope is a metal shield 18. Spaced from the shield 18 is a metal substrate 20, on one face of which is mounted a rectangular photocathode wafer 26 of monocrystalline In Ga As (x 0.72) about 2 cm (centimeters) long, 0.5 cm wide, and 0.5 mm (millimeters) thick. Between the shield 18 and the metal substrate 20 is a resistance heating filament 22 for heating the substrate 20 and the photocathode 26.
  • a grid electrode 28 angularly spaced from the photocathode 26, and generally perpendicular to the direction of light input to the photocathode 26.
  • a series of eight copper-beryllium alloy dynodes 30, and an anode 32 are arranged in the grid 28.
  • the general direction of average electron trajectories from the photocathode 26 to the anode 32 are indicated by the dashed lines 38.
  • a resistance-heated cesium vapor-generating channel 4'0 and an oxygengenerating channel 42 for processing of the photocathode 26 are mounted inside the tube 10 near the base 14, as shown in FIG. 1.
  • a platinumantimony alloy bead 43 with a ceramic shield 45 is mounted in the upper part of the tube 10, facing an upper portion of the wall of the envelope 12.
  • a layer 44 of antimony incompletely reacted with cesium, about 10 pm (micrometers) thick, is disposed opposite the bead 43 on the inside upper portion of the wall of ;the envelope 12.
  • a III-V compound cathode activated by the novel layer 44 serves as a cesium buffer source during the processing described below.
  • the photocathode 26 of the tube of FIG. 1 is activated as follows: Afterthe internal elements of the tube 10 have been assembled inside the envelope 12, the tube 10 is heated to a bakeout temperature of about 350C for several hours while being simultaneously evacuated through the exhaust tubulation in the base 14 to clean the internal components. The evacuating is continued throughout the processing thereafter. Then the tube is allowed to cool enough to permit handling. Current is passed through the heating filament 22 to heat the cathode 26 along to near decomposition temperature for a short time to prepare the surface of the cathode 26 for activation.
  • antimony is vapor-deposited to a thickness of about 10 am on a small area of the upper side wall portion of the glass envelope 12 by resistance heating of the alloy bead 43.
  • the antimony layer reacts with cesium during later cesium processing steps to form the cesium buffer layer 44.
  • Cesium vapor is now generated in the interior by resistance heating of the cesium channel 40, while the photosensitivity of the photocathode 26 is monitored.
  • the photocathode is exposed to the cesium vapor until its photosensitivity has passed a peak, after which the cesium generation is terminated.
  • Oxygen is now generated from the oxygen channel 42 by resistance heating until the photosensitivity of the photocathode 26 again passes a peak, after which the oxygen generation is terminated.
  • the tube 10 is heated to about 150C, until the photosensitivity of the photocathode 26 becomes substantially constant, then allowed to cool to room temperature. The photocathode 26 is now stable. The tube 10 is then sealed off under vacuum at the exhaust tubulation 14.
  • the cesium vapor When the cesium vapor is first generated in the tube 10, a portion of the cesium combines with the antimony of the buffer source layer 44 on the wall of the envelope 12 to form a compound of antimony incompletely reacted with cesium. Cesium also is adsorbed on the crystal surface of the photocathode 26 to form a workfunction-reducing layer. As the tube 10 is heated from below 100C to the higher temperature of 150C, cesium is released at an increasing rate into the interior of the tube 10 from the buffer source layer 44 by decomposition, thus simultaneously increasing the cesium concentration to which the photocathode 26 is exposed. A dynamic balance condition is established at the surface of the photocathode 26, which prevents a substantial loss of cesium from the work-functionreducing layer.
  • novel invention is applicable to activation of any III-V semiconductor compound cathode coated with a 5 cesium-containing work-function-reducing layer.
  • III-V compounds While the higher temperature activation of the preferred embodiment was 150C, a cathode heated to any temperature above 100C in the presence of a small amount of cesium vapor, as provided by a cesium compound buffer source, can be expected to have improved stability.
  • a cathode heated to any temperature above 100C in the presence of a small amount of cesium vapor, as provided by a cesium compound buffer source can be expected to have improved stability.
  • Other III-V compounds, such as gallium phosphide for example, are generally not exposed to oxygen or fluorine during the processing.
  • the cesium buffer source may be provided anywhere in the envelope where its electron emissive properties do not interfere with the normal operation of the tube. For example, since cesium antimonide is photoemissive, it would be undesirable to place the buffer source layer where light incident on it may result in spuriously emitted electrons entering the multiplier.
  • the buffer source should be electrically passive, since neither its primary nor secondary emission characteristics are particularly useful.
  • the cesium-antimony compound of the cesium buffer source of the preferred embodiment tends to produce an optimum cesium equilibrium in the tube at high temperatures because, as a result of slight decomposition, sufficient cesium vapor is generated from it to prevent excessive loss of cesiumfrom the III-V compound cathode. At the same time, the cesium is sufficiently bound in the cesium-antimony at lower temperatures to prevent the remaining of excess cesium which might be deleterious to the cathode..Other cesium compounds which decompose at elevated temperatures above 100C may be used for the buffer source instead of a cesium-antimony compound. Examples of such compounds are cesium-bismuth, cesiumgold, or cesium-graphite. However, the decomposition should begin at a low enough temperature to provide some cesium at about 150C.
  • III-V semiconductor compound cathode comprising the steps of:
  • the buffer source is a material selected from the group consisting 'of antimony, bismuth, gold, and graphite.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Common Detailed Techniques For Electron Tubes Or Discharge Tubes (AREA)
  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
  • Cold Cathode And The Manufacture (AREA)
  • Electron Sources, Ion Sources (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
US323746A 1973-01-15 1973-01-15 Method of making a iii-v compound electron-emissive cathode Expired - Lifetime US3858955A (en)

Priority Applications (12)

Application Number Priority Date Filing Date Title
US323746A US3858955A (en) 1973-01-15 1973-01-15 Method of making a iii-v compound electron-emissive cathode
IT27369/73A IT992789B (it) 1973-01-15 1973-07-31 Metodo di fabbricazione di un catodo ad emissione elettronica di un composto di elementi dei gruppi iii v e tubo adatto per tale metodo
NL7313189A NL7313189A (it) 1973-01-15 1973-09-25
SU7301958617A SU568405A3 (ru) 1973-01-15 1973-09-26 Способ изготовлени фотокатода
DD173922A DD107172A5 (it) 1973-01-15 1973-10-08
SE7313657A SE387773B (sv) 1973-01-15 1973-10-08 Sett att framstella en katod av en iii/v-halvledarforening
DE19732350872 DE2350872C3 (de) 1973-01-15 1973-10-10 Verfahren zum Herstellen einer Photokathode für eine Elektronenröhre
AU61278/73A AU482492B2 (en) 1973-01-15 1973-10-11 Method of making a iii-v compound electron-emissive cathode, and tube suited for such method
FR7336613A FR2214169B1 (it) 1973-01-15 1973-10-12
JP11525073A JPS52668B2 (it) 1973-01-15 1973-10-12
CA183,373A CA993030A (en) 1973-01-15 1973-10-15 Method of making a iii-v compound electron-emissive cathode, and tube suited for such method
GB5214173A GB1453965A (en) 1973-01-15 1973-11-09 Electron-emissive cathodes

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US323746A US3858955A (en) 1973-01-15 1973-01-15 Method of making a iii-v compound electron-emissive cathode

Publications (1)

Publication Number Publication Date
US3858955A true US3858955A (en) 1975-01-07

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US323746A Expired - Lifetime US3858955A (en) 1973-01-15 1973-01-15 Method of making a iii-v compound electron-emissive cathode

Country Status (10)

Country Link
US (1) US3858955A (it)
JP (1) JPS52668B2 (it)
CA (1) CA993030A (it)
DD (1) DD107172A5 (it)
FR (1) FR2214169B1 (it)
GB (1) GB1453965A (it)
IT (1) IT992789B (it)
NL (1) NL7313189A (it)
SE (1) SE387773B (it)
SU (1) SU568405A3 (it)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2813218A1 (de) * 1977-04-04 1978-10-12 Machlett Lab Inc Bildverstaerkerroehre
US4145101A (en) * 1975-04-18 1979-03-20 Hitachi, Ltd. Method for manufacturing gas insulated electrical apparatus
US4426596A (en) 1981-02-24 1984-01-17 Rca Corporation Photomultiplier tube having a heat shield with alkali vapor source attached thereto
WO1998052228A1 (en) * 1997-05-16 1998-11-19 Skion Corporation Cold cathode electron emitter and display structure
WO2007109815A1 (de) 2006-03-24 2007-10-04 Alvatec Production And Sales Gesmbh Alkalimetall- oder erdalkalimetall-verdampferquelle
CN103165361A (zh) * 2013-03-13 2013-06-19 清华大学深圳研究生院 一种含铯化合物阴极的制备方法及该阴极
CN111863569A (zh) * 2020-07-20 2020-10-30 南京工程学院 一种提高砷化镓光电阴极发射性能的激活方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2401734A (en) * 1940-10-08 1946-06-11 Rca Corp Photoelectric electron multiplier
US2877078A (en) * 1954-04-13 1959-03-10 Du Mont Allen B Lab Inc Method of treating phototubes
US3372967A (en) * 1966-07-06 1968-03-12 Rca Corp Method of making a multi-alkali cathode
US3658400A (en) * 1970-03-02 1972-04-25 Rca Corp Method of making a multialkali photocathode with improved sensitivity to infrared light and a photocathode made thereby
US3712700A (en) * 1971-01-18 1973-01-23 Rca Corp Method of making an electron emitter device
US3753023A (en) * 1971-12-03 1973-08-14 Rca Corp Electron emissive device incorporating a secondary electron emitting material of antimony activated with potassium and cesium

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2401734A (en) * 1940-10-08 1946-06-11 Rca Corp Photoelectric electron multiplier
US2877078A (en) * 1954-04-13 1959-03-10 Du Mont Allen B Lab Inc Method of treating phototubes
US3372967A (en) * 1966-07-06 1968-03-12 Rca Corp Method of making a multi-alkali cathode
US3658400A (en) * 1970-03-02 1972-04-25 Rca Corp Method of making a multialkali photocathode with improved sensitivity to infrared light and a photocathode made thereby
US3712700A (en) * 1971-01-18 1973-01-23 Rca Corp Method of making an electron emitter device
US3753023A (en) * 1971-12-03 1973-08-14 Rca Corp Electron emissive device incorporating a secondary electron emitting material of antimony activated with potassium and cesium

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4145101A (en) * 1975-04-18 1979-03-20 Hitachi, Ltd. Method for manufacturing gas insulated electrical apparatus
DE2813218A1 (de) * 1977-04-04 1978-10-12 Machlett Lab Inc Bildverstaerkerroehre
US4426596A (en) 1981-02-24 1984-01-17 Rca Corporation Photomultiplier tube having a heat shield with alkali vapor source attached thereto
US5908699A (en) * 1996-10-11 1999-06-01 Skion Corporation Cold cathode electron emitter and display structure
WO1998052228A1 (en) * 1997-05-16 1998-11-19 Skion Corporation Cold cathode electron emitter and display structure
WO2007109815A1 (de) 2006-03-24 2007-10-04 Alvatec Production And Sales Gesmbh Alkalimetall- oder erdalkalimetall-verdampferquelle
CN103165361A (zh) * 2013-03-13 2013-06-19 清华大学深圳研究生院 一种含铯化合物阴极的制备方法及该阴极
CN103165361B (zh) * 2013-03-13 2015-11-25 清华大学深圳研究生院 一种含铯化合物阴极的制备方法及该阴极
CN111863569A (zh) * 2020-07-20 2020-10-30 南京工程学院 一种提高砷化镓光电阴极发射性能的激活方法
CN111863569B (zh) * 2020-07-20 2023-04-18 南京工程学院 一种提高砷化镓光电阴极发射性能的激活方法

Also Published As

Publication number Publication date
SE387773B (sv) 1976-09-13
FR2214169A1 (it) 1974-08-09
SU568405A3 (ru) 1977-08-05
FR2214169B1 (it) 1977-05-27
AU6127873A (en) 1975-04-17
DE2350872B2 (de) 1976-05-06
NL7313189A (it) 1974-07-17
DE2350872A1 (de) 1974-07-18
GB1453965A (en) 1976-10-27
CA993030A (en) 1976-07-13
DD107172A5 (it) 1974-07-12
JPS49106280A (it) 1974-10-08
JPS52668B2 (it) 1977-01-10
IT992789B (it) 1975-09-30

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