US3868523A - Semitransparent photocathode - Google Patents

Semitransparent photocathode Download PDF

Info

Publication number
US3868523A
US3868523A US412704A US41270473A US3868523A US 3868523 A US3868523 A US 3868523A US 412704 A US412704 A US 412704A US 41270473 A US41270473 A US 41270473A US 3868523 A US3868523 A US 3868523A
Authority
US
United States
Prior art keywords
photocathode
substrate
intermediate layer
active layer
layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US412704A
Other languages
English (en)
Inventor
Anton Martin Klopfer
Siegfried Garbe
Gunter Frank
Manfred Peterek
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
US Philips Corp
Original Assignee
US Philips Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by US Philips Corp filed Critical US Philips Corp
Application granted granted Critical
Publication of US3868523A publication Critical patent/US3868523A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B19/00—Liquid-phase epitaxial-layer growth
    • C30B19/12—Liquid-phase epitaxial-layer growth characterised by the substrate
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/34—Photo-emissive cathodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2201/00—Electrodes common to discharge tubes
    • H01J2201/34—Photoemissive electrodes
    • H01J2201/342—Cathodes
    • H01J2201/3421—Composition of the emitting surface
    • H01J2201/3423—Semiconductors, e.g. GaAs, NEA emitters

Definitions

  • Such a photocathode may consist in particular of 3,309,553 3/l967 Kroemer 313/108 a substrate of an intermediate layer of 3,575,628 4/1971 Word 313/95 l-1 with and an active layer of GaAs- 3,667,007 5/1972 Kressel et al.
  • the invention relates to a semitransparent photocathode from 3-5 semiconductor compounds having a substrate, an intermediate layer and a p-doped active layer, the energy gap of the p-doped active layer being smaller than that of the p-doped intermediate layer.
  • a semitransparent or transparent photocathode is to be understood to mean an arrangement in which the light is radiated from one side on a photosensitive layer but the excited electrons are emitted in the vacuum on the other side of the photocathode. Because reproduction problems can easily be solved with transparent photocathodes, they are of particular importance for a number of applications, such as photomultipliers, image converters in particular such of the close proximity type but also camera tubes of the type of the vidicon with internal amplification.
  • the quantum efficiency Y of a 3-5-semiconduct0r photocathode is determined by surface properties and volume properties, in particular by the diffusion length of the electrons.
  • the diffusion length L should hence be as large as possible.
  • the diffusion length also depends on impurities and in particular on the crystal perfection.
  • the diffusion length of the electrons should be large, preferably larger than the layer thickness of the active layer.
  • the substrate should have a rather large energy gap and be p-conductive in order that at the interface with the layer a reflection of the electrons which diffuse towards the interface on the light entrance side is ensured in the direction of the electron-emitting side of the layer of the photocathode by a barrier in the conductance band.
  • Such a layer is difficult to manufacture and, due to the close relation between substrate, intermediate layer and active layer as regards its composition, does not allow such a selection of the substrate and intermediate layer, respectively, as would be desirable in connection with an optimum sensitivity and/or optical wide band condition of the photocathode.
  • the substrate after growing the layers, in the form of a ring or frame so that in the active part of the photocathode the intermediate layer and the active layer are self-supporting.
  • FIG. 1a shows another embodiment of the invention.
  • FIG. 2 shows the energy band diagram associated with the photocathode shown in FIG. 1,
  • FIG. 3 shows the spectral sensitivity (quantum efficiency) Y of the photocathode shown in FIG. 1.
  • FIG. 1 shows diagrammatically a first embodiment of a semitransparent photocathode according to the invention.
  • An approximately 5-15 pm thick, weakly pdoped Al,Ga ,As layer 2 is provided on an approximately 150 um thick GaP substrate 1, wherein x 0.8.
  • a 2-4pm thick p doped GaAs layer 3 is provided thereon according to the method of the multi-layer epitaxy.
  • the lattice constant a of the substrate 1 is 5.45 A, that of the layer 2 is 5.662 A and that of the layer 3 is 5.6535 A.
  • the layer 3 is covered at its surface with a monolayer 4 of cesium and oxygen.
  • FIG. la shows another embodiment in which the substrate l 1 is in the form of a ring or frame, the central portion of which has been etched away.
  • Substrate 11 supports an intermediate layer 12 approx. -15 pm thick and consists of Al Ga As on a substrate of GaP.
  • Over the intermediate layer a layer 13 ofp GaAs is provided on which a monolayer 14 of cesium and oxygen is provided as in the previous embodiment.
  • the photocathode shown diagrammatically in FIG. 1 can be manufactured according to known methods, for example, by means of the multilayer epitaxy from the liquid phase.
  • the composition of the melt for the Al,Ga ,As epitaxy was: 1.6765 gGa; 0.06 g GaAs; 0.045 g Al and 0.0169 g Zn.
  • the epitaxy of the Al,Ga, ,As layer of l2,u.m thickness occurs upon cooling the melt from 934C to 836C at a cooling rate of 3.3C per minute, duration 29 minutes and seconds.
  • a rapid change during the second melt is necessary so as to avoid an oxidation of the AI Ga As-Iayer (with x 0.8) also during the flow of purified hydrogen.
  • FIG. 3 shows the quantum efficiency Y (electronlimpinging photon) measured in transmission of a photocathode manufactured in this manner.
  • An SiO layer on the GaP substrate to reduce the reflection on the light entrance side can additionally produce an amplification of the light excitation in the GaAs photoemission layer at least for a limited wavelength range.
  • Ga As After removing the coating layer and providing an SiO layer on the A1,. Ga As, a self-supporting layer in the sequence SiO Al Ga As and GaAs remains in the inner part, the GaAs layer having the properties required for a high photoemission in transmission.
  • Transparent photocathodes according to the invention may furthermore be realized in that substrates of sapphire or spinel are used as the starting material on which the intermediate layer and the active layer are depostied by epitaxy from the liquid phase or gaseous phase.
  • starting material may be a sapphire substrate on which a monocrystalline 5-20um thick pdoped AlAs layer is produced as an intermediate layer by epitaxy from the gaseous phase with trimethylaluminum and arsenic hydrogen.
  • the subsequent provision of the active GaAs layer may succeed immediately by switching to trimethylgallium.
  • the intermediate layer from Al,Ga ,As adapted to the above layer of GaAs, with x 0.8 as described above, may be provided by epitaxy from the liquid phase.
  • a ternary compound such as (Ga, In) As or In (As, P) as an active layer
  • a ternary compound such as (Ga, In) As or In (As, P) as an active layer
  • GaP mixed spinel systems
  • Mg(ln,Ga O mixed spinel systems
  • intermediate layers are to be used ternary semiconductor compounds having the same grid parameters as the active layer but with a larger energy gap in the interest of a wide optical transparency.
  • Examples are: (or Ga ln As with an energy gap of 1.18 Ev the matching of the grid constant can be achieved by an intermediate layer of Ga ln P with an energy gap of 1.9 eV, or by an intermediate layer of Al ln As with an energy gap of 2.1 eV or also by an intermediate layer of Al Ga ln P with an energy gap of 2.5 eV.
  • a semitransparent photocathode of Ill-V semiconductor compounds having a substrate, an intermediate layer and an active layer, the energy gap of the active layer being smaller than that of the intermediate layer and the active and the intermediate layer being pdoped, the intermediate layer having a composition having elements which differ from those of the substrate and the active layer and a lattice constant differing from the lattice constant of the active layer by-less than 0.3% and from the lattice constant of the substrate up to several per cent.
  • the active layer consists of a material selected from the group consisting of GaAs, (Ga, In) As and In (As, P).

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Common Detailed Techniques For Electron Tubes Or Discharge Tubes (AREA)
US412704A 1972-12-16 1973-11-05 Semitransparent photocathode Expired - Lifetime US3868523A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19722261757 DE2261757A1 (de) 1972-12-16 1972-12-16 Semitransparente photokathode

Publications (1)

Publication Number Publication Date
US3868523A true US3868523A (en) 1975-02-25

Family

ID=5864639

Family Applications (1)

Application Number Title Priority Date Filing Date
US412704A Expired - Lifetime US3868523A (en) 1972-12-16 1973-11-05 Semitransparent photocathode

Country Status (3)

Country Link
US (1) US3868523A (en(2012))
JP (1) JPS4990869A (en(2012))
DE (1) DE2261757A1 (en(2012))

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3972770A (en) * 1973-07-23 1976-08-03 International Telephone And Telegraph Corporation Method of preparation of electron emissive materials
US4012760A (en) * 1974-03-18 1977-03-15 Hamamatsu Terebi Kabushiki Kaisha Semiconductor cold electron emission device
US4019082A (en) * 1975-03-24 1977-04-19 Rca Corporation Electron emitting device and method of making the same
US4498225A (en) * 1981-05-06 1985-02-12 The United States Of America As Represented By The Secretary Of The Army Method of forming variable sensitivity transmission mode negative electron affinity photocathode
US4518980A (en) * 1981-06-03 1985-05-21 U.S. Philips Corporation Semiconductor device for the vacuum-emission of electrons
US4644221A (en) * 1981-05-06 1987-02-17 The United States Of America As Represented By The Secretary Of The Army Variable sensitivity transmission mode negative electron affinity photocathode
US4807006A (en) * 1987-06-19 1989-02-21 International Business Machines Corporation Heterojunction interdigitated schottky barrier photodetector
US5448084A (en) * 1991-05-24 1995-09-05 Raytheon Company Field effect transistors on spinel substrates
US5591986A (en) * 1993-09-02 1997-01-07 Hamamatsu Photonics K.K. Photoemitter electron tube and photodetector
US6005257A (en) * 1995-09-13 1999-12-21 Litton Systems, Inc. Transmission mode photocathode with multilayer active layer for night vision and method
US20070034987A1 (en) * 2005-06-01 2007-02-15 Intevac Inc. Photocathode structure and operation
US10804428B2 (en) 2018-11-16 2020-10-13 International Business Machines Corporation High efficiency light emitting diode (LED) with low injection current

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3959045A (en) * 1974-11-18 1976-05-25 Varian Associates Process for making III-V devices
DE3310303A1 (de) * 1983-03-22 1984-09-27 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Bildverstaerkervorrichtung

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3309553A (en) * 1963-08-16 1967-03-14 Varian Associates Solid state radiation emitters
US3575628A (en) * 1968-11-26 1971-04-20 Westinghouse Electric Corp Transmissive photocathode and devices utilizing the same
US3667007A (en) * 1970-02-25 1972-05-30 Rca Corp Semiconductor electron emitter
US3696262A (en) * 1970-01-19 1972-10-03 Varian Associates Multilayered iii-v photocathode having a transition layer and a high quality active layer

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE210194C (en(2012)) *

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3309553A (en) * 1963-08-16 1967-03-14 Varian Associates Solid state radiation emitters
US3575628A (en) * 1968-11-26 1971-04-20 Westinghouse Electric Corp Transmissive photocathode and devices utilizing the same
US3696262A (en) * 1970-01-19 1972-10-03 Varian Associates Multilayered iii-v photocathode having a transition layer and a high quality active layer
US3667007A (en) * 1970-02-25 1972-05-30 Rca Corp Semiconductor electron emitter

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3972770A (en) * 1973-07-23 1976-08-03 International Telephone And Telegraph Corporation Method of preparation of electron emissive materials
US4012760A (en) * 1974-03-18 1977-03-15 Hamamatsu Terebi Kabushiki Kaisha Semiconductor cold electron emission device
US4019082A (en) * 1975-03-24 1977-04-19 Rca Corporation Electron emitting device and method of making the same
US4498225A (en) * 1981-05-06 1985-02-12 The United States Of America As Represented By The Secretary Of The Army Method of forming variable sensitivity transmission mode negative electron affinity photocathode
US4644221A (en) * 1981-05-06 1987-02-17 The United States Of America As Represented By The Secretary Of The Army Variable sensitivity transmission mode negative electron affinity photocathode
US4518980A (en) * 1981-06-03 1985-05-21 U.S. Philips Corporation Semiconductor device for the vacuum-emission of electrons
US4807006A (en) * 1987-06-19 1989-02-21 International Business Machines Corporation Heterojunction interdigitated schottky barrier photodetector
US5448084A (en) * 1991-05-24 1995-09-05 Raytheon Company Field effect transistors on spinel substrates
US5591986A (en) * 1993-09-02 1997-01-07 Hamamatsu Photonics K.K. Photoemitter electron tube and photodetector
US5747826A (en) * 1993-09-02 1998-05-05 Hamamatsu Photonics K.K. Photoemitter electron tube, and photodetector
US6005257A (en) * 1995-09-13 1999-12-21 Litton Systems, Inc. Transmission mode photocathode with multilayer active layer for night vision and method
US6110758A (en) * 1995-09-13 2000-08-29 Litton Systems, Inc. Transmission mode photocathode with multilayer active layer for night vision and method
US20070034987A1 (en) * 2005-06-01 2007-02-15 Intevac Inc. Photocathode structure and operation
US7531826B2 (en) * 2005-06-01 2009-05-12 Intevac, Inc. Photocathode structure and operation
US10804428B2 (en) 2018-11-16 2020-10-13 International Business Machines Corporation High efficiency light emitting diode (LED) with low injection current

Also Published As

Publication number Publication date
JPS4990869A (en(2012)) 1974-08-30
DE2261757A1 (de) 1974-06-20

Similar Documents

Publication Publication Date Title
US3868523A (en) Semitransparent photocathode
US3696262A (en) Multilayered iii-v photocathode having a transition layer and a high quality active layer
Bell et al. 3-5 compound photocathodes: A new family of photoemitters with greatly improved performance
Martinelli et al. The application of semiconductors with negative electron affinity surfaces to electron emission devices
US3894332A (en) Solid state radiation sensitive field electron emitter and methods of fabrication thereof
US4644221A (en) Variable sensitivity transmission mode negative electron affinity photocathode
US3699401A (en) Photoemissive electron tube comprising a thin film transmissive semiconductor photocathode structure
CA1114050A (en) Manufacture of solar cells
Williams et al. Current status of negative electron affinity devices
US5354694A (en) Method of making highly doped surface layer for negative electron affinity devices
US3575628A (en) Transmissive photocathode and devices utilizing the same
JPS5951700B2 (ja) ３−５族装置の製造方法
KR930013772A (ko) 야간 투시 장치 의 투과 모드 인듐 갈륨 비소(InGaAs)광전음극
JPH09259795A (ja) 冷電子放出表示装置
US4498225A (en) Method of forming variable sensitivity transmission mode negative electron affinity photocathode
US4286373A (en) Method of making negative electron affinity photocathode
US3814996A (en) Photocathodes
US3972770A (en) Method of preparation of electron emissive materials
JPH0936427A (ja) 半導体装置及びその製造方法
US6831341B2 (en) Photocathode having AlGaN layer with specified Mg content concentration
US4161418A (en) Ionized-cluster-beam deposition process for fabricating p-n junction semiconductor layers
KR100423849B1 (ko) 매우 얇은 보호막을 갖는 광음극
JPH0896705A (ja) 半導体光電陰極及び光電管
US5982093A (en) Photocathode and electron tube having enhanced absorption edge characteristics
US4518980A (en) Semiconductor device for the vacuum-emission of electrons