EP0066926B1 - Dispositif semiconducteur, émetteur d'électrons, dont la couche active possède un gradient de dopage - Google Patents

Dispositif semiconducteur, émetteur d'électrons, dont la couche active possède un gradient de dopage

Info

Publication number
EP0066926B1
EP0066926B1 EP82200648A EP82200648A EP0066926B1 EP 0066926 B1 EP0066926 B1 EP 0066926B1 EP 82200648 A EP82200648 A EP 82200648A EP 82200648 A EP82200648 A EP 82200648A EP 0066926 B1 EP0066926 B1 EP 0066926B1
Authority
EP
European Patent Office
Prior art keywords
active layer
doping
semiconductor
semiconductor device
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
Application number
EP82200648A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0066926A1 (fr
Inventor
Pierre Guittard
Philippe Jarry
Alphonse Ducarre
Lazhar Haji
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.)
Laboratoires dElectronique Philips SAS
Koninklijke Philips NV
Original Assignee
Laboratoires dElectronique et de Physique Appliquee
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
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 Laboratoires dElectronique et de Physique Appliquee, Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical Laboratoires dElectronique et de Physique Appliquee
Publication of EP0066926A1 publication Critical patent/EP0066926A1/fr
Application granted granted Critical
Publication of EP0066926B1 publication Critical patent/EP0066926B1/fr
Expired legal-status Critical Current

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Classifications

    • 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
    • H01J1/32—Secondary-electron-emitting electrodes
    • 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

  • the invention relates to a semiconductor device having a surface capable of emitting electrons in response to electronic bombardment or to the impact of light radiation.
  • the invention relates to electronic or optoelectronic devices, such as photocathodes used in picture tubes and photomultipliers, which convert between photons and electrons, or dynodes used in photomultipliers, which operate by secondary electronic emission.
  • the object of the invention is to obtain semiconductor devices whose efficiency is improved, that is to say whose excitation, diffusion and electronic emission are simultaneously improved.
  • the invention is based on the fact that these functions are separable.
  • the semiconductor device according to the present invention is remarkable in that it comprises a so-called active semiconductor layer, flush with the emitting surface, the doping of which increases when the distance to said emitting surface decreases.
  • the active layer of this device has characteristics which vary as a function of the distance from the emitting surface, so that in depth, the diffusion length is high due to low doping, which makes it possible to improve the scattering of excited electrons, and that on the surface, the probability of emission is high due to strong doping.
  • the semiconductor active layer consists of at least two different doping zones, the zone close to the emitting surface being relatively more doped.
  • the doping varies "in steps" instead of continuously varying, but the separation of the broadcasting and transmission functions is also ensured.
  • the active layer is made of a III-V compound, for example gallium arsenide, of type p conductivity, of a thickness less than 10 microns, and has a doping which varies radially between 10 18 and 10 19 atoms / cm 3 continuously or discontinuously.
  • a III-V compound for example gallium arsenide, of type p conductivity, of a thickness less than 10 microns, and has a doping which varies radially between 10 18 and 10 19 atoms / cm 3 continuously or discontinuously.
  • Electron emitting devices generally fall into two types, depending on their mode of operation in transmission or reflection.
  • the invention is intended to apply to devices of both types, but for simplicity the following description will rather refer to devices of the first type, without being able to draw any limitation therefrom.
  • FIG. 1 represents a photocathode with an inverted structure, operating in transmission, capable of emitting electrons as a result of the absorption of light radiation.
  • This photon-electron transducer does indeed belong to the devices targeted by the present invention, and will serve as the basis for its description.
  • Such a photocathode is constituted by the sealing on a glass substrate 1 (or of corundum) of a complex semiconductor structure, by means of a sealing layer 2, for example in a glass of the short type such as that described in the French patent application, number 2,300,413, filed on February 4, 1975, in the name of the Applicant.
  • the semiconductor structure consists of a semiconductor layer 3, called “active layer”, generally made of gallium arsenide, of p conductivity type, and an additional layer 4, called “passivation layer”, placed between the glass and the active layer, the function of which is to decrease the rate of recombination at the interface.
  • an active layer 3 of GaAs (p) it is composed of gallium and aluminum arsenide, Ga i -y Aly As, also of p conductivity type.
  • the active semiconductor layer 3 has on its outer face, intended to be subjected to vacuum, a state of negative apparent electronic affinity, obtained for example, by a conventional surface treatment, well known in the prior art, of covering with cesium and oxygen.
  • Such a glass-semiconductor composite material is not obtained immediately by simple bonding, but initially requires the growth of a double hetero-structure on a substrate, then the subsequent removal by pickling. chemical of the first heterostructure.
  • the production of this structure therefore requires epitaxial growth, on a GaAs substrate 5, shown in dotted lines in FIG. 1 as destined to disappear, of a first layer 6 of Ga 1-x Al x A s , for which x typically equals 0.5, the so-called “chemical stop” layer (or blocking, because it makes it possible to stop the pickling process of the substrate, which would otherwise continue in the active layer 3), a second layer of GaAs called “active layer” 3, of p conductivity type, obtained for example by doping with zinc (Zn) or germanium (Ge), and finally a third layer 4 of Ga 1-y Al y As, for which varies there between 0.25 and 1, according to the desired characteristics, the so-called passivation layer, and the functions of which have been specified previously.
  • the growth of these layers can be carried out by epitaxy in the liquid phase or in the vapor phase, for example according to the organometallic method.
  • This structure is then bonded to a substrate 1 of glass (or corundum), which plays a role of mechanical support and optical window, this sealing being able to be carried out by means of a layer of glass 2, layer 4 known as passivation being the closest to the glass substrate 1, which explains in particular the mention of photocathode "with inverted structure".
  • the substrate 5 and the chemical barrier layer 6 are removed by chemical pickling; an example of a bath used for the chemical attack on the GaAs substrate 1 is a solution of NH 4 0H (- 40%) at 5% by volume in H 2 0 2 (- 30%), a bath which has the advantage of '' a relatively high attack speed and excellent selectivity vis-à-vis the stop layer 6.
  • This last layer 6 is then removed, for example by a commercial dilute hydrofluoric acid (HF) bath (40% V), a bath which practically does not attack the GaAs.
  • HF dilute hydrofluoric acid
  • the active layer 3 is brought to an optimum thickness if necessary, for example by a light chemical pickling, then activated, in an ultra-vacuum frame, in order to obtain a photocathode, if that is its destination. .
  • the electron thus excited reaches the GaAs / vacuum interface, it can be emitted in vacuum, provided that the material is placed in a state of apparent negative affinity.
  • the probability of electronic emission depends on several factors, including the crystal orientation, the doping, etc ... and in particular, it is all the greater the higher the doping level.
  • the invention aims to improve the apparent diffusion length by proposing a new structure for the active layer.
  • the active layer 3 has a doping which increases when the distance to the emitting surface decreases.
  • the active layer of a photoemitter is obtained in the form of two different doping zones, in gallium arsenide of p conductivity type, doped with a low coefficient material diffusion such as germanium (Ge).
  • the continuous variation of doping can be obtained either by a variable dosage of impurities in the process of growth, for example in the epitaxy reactor in the vapor phase, or by diffusion thanks to the choice of an impurity do pante with greater diffusion coefficient, such as zinc (Zn).
  • This structure can also be obtained with any other semiconductor material, such as binary or pseudo-binary compounds III-V or II-VI, etc., the values of the compositions, dopings and thicknesses of layers then being adapted to each case. and easily calculable by the practitioner, without it being done for that purpose.
  • any other semiconductor material such as binary or pseudo-binary compounds III-V or II-VI, etc.
  • the invention is not limited to photocathodes, but also finds its application for the production of dynodes, generally in any semiconductor device emitting electrons.
  • FIG. 2 is a network of theoretical curves, giving an example of the variation of the sensitivity (on the abscissa, in ⁇ A / lumen) in white light (2854 K), photocathodes with inverted structure, in accordance with the present invention, as a function the thickness of the active layer 3 of GaAs (on the ordinate, in ⁇ m), for different values of the apparent electron scattering length (parameter, in ⁇ m), and for which P represents the probability of photoelectron emission, and S the photoelectron recombination speed at the GaAs / GaAl As interface.

Landscapes

  • Common Detailed Techniques For Electron Tubes Or Discharge Tubes (AREA)
  • Cold Cathode And The Manufacture (AREA)
EP82200648A 1981-06-03 1982-05-27 Dispositif semiconducteur, émetteur d'électrons, dont la couche active possède un gradient de dopage Expired EP0066926B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8110993 1981-06-03
FR8110993A FR2507386A1 (fr) 1981-06-03 1981-06-03 Dispositif semi-conducteur, emetteur d'electrons, dont la couche active possede un gradient de dopage

Publications (2)

Publication Number Publication Date
EP0066926A1 EP0066926A1 (fr) 1982-12-15
EP0066926B1 true EP0066926B1 (fr) 1985-02-13

Family

ID=9259150

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82200648A Expired EP0066926B1 (fr) 1981-06-03 1982-05-27 Dispositif semiconducteur, émetteur d'électrons, dont la couche active possède un gradient de dopage

Country Status (5)

Country Link
US (1) US4518980A (enExample)
EP (1) EP0066926B1 (enExample)
JP (1) JPS57210539A (enExample)
DE (1) DE3262303D1 (enExample)
FR (1) FR2507386A1 (enExample)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4677342A (en) * 1985-02-01 1987-06-30 Raytheon Company Semiconductor secondary emission cathode and tube
DE69030145T2 (de) * 1989-08-18 1997-07-10 Galileo Electro Optics Corp Kontinuierliche Dünnschicht-Dynoden
US5680008A (en) * 1995-04-05 1997-10-21 Advanced Technology Materials, Inc. Compact low-noise dynodes incorporating semiconductor secondary electron emitting materials
JPH1196896A (ja) * 1997-09-24 1999-04-09 Hamamatsu Photonics Kk 半導体光電面
US7161162B2 (en) * 2002-10-10 2007-01-09 Applied Materials, Inc. Electron beam pattern generator with photocathode comprising low work function cesium halide
CN100426439C (zh) * 2003-12-24 2008-10-15 中国科学院半导体研究所 中浓度p型掺杂透射式砷化镓光阴极材料及其制备方法
US10692683B2 (en) * 2017-09-12 2020-06-23 Intevac, Inc. Thermally assisted negative electron affinity photocathode

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3959038A (en) * 1975-04-30 1976-05-25 The United States Of America As Represented By The Secretary Of The Army Electron emitter and method of fabrication
FR2300413A1 (fr) * 1975-02-04 1976-09-03 Labo Electronique Physique Fenetre

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3478213A (en) * 1967-09-05 1969-11-11 Rca Corp Photomultiplier or image amplifier with secondary emission transmission type dynodes made of semiconductive material with low work function material disposed thereon
US3631303A (en) * 1970-01-19 1971-12-28 Varian Associates Iii-v cathodes having a built-in gradient of potential energy for increasing the emission efficiency
US3981755A (en) * 1972-11-24 1976-09-21 U.S. Philips Corporation Photocathode manufacture
DE2261757A1 (de) * 1972-12-16 1974-06-20 Philips Patentverwaltung Semitransparente photokathode
GB1446592A (en) * 1973-01-09 1976-08-18 English Electric Valve Co Ltd Dynode structures
AU7731575A (en) * 1974-01-18 1976-07-15 Nat Patent Dev Corp Heterojunction devices
US3959045A (en) * 1974-11-18 1976-05-25 Varian Associates Process for making III-V devices
GB1536412A (en) * 1975-05-14 1978-12-20 English Electric Valve Co Ltd Photocathodes
DE2909956A1 (de) * 1979-03-14 1980-09-18 Licentia Gmbh Halbleiter-glas-verbundwerkstoff

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2300413A1 (fr) * 1975-02-04 1976-09-03 Labo Electronique Physique Fenetre
US3959038A (en) * 1975-04-30 1976-05-25 The United States Of America As Represented By The Secretary Of The Army Electron emitter and method of fabrication

Also Published As

Publication number Publication date
FR2507386A1 (fr) 1982-12-10
DE3262303D1 (en) 1985-03-28
FR2507386B1 (enExample) 1984-05-04
JPH0411973B2 (enExample) 1992-03-03
US4518980A (en) 1985-05-21
EP0066926A1 (fr) 1982-12-15
JPS57210539A (en) 1982-12-24

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