WO2001054204A1 - Dispositif a semi-conducteur - Google Patents

Dispositif a semi-conducteur Download PDF

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Publication number
WO2001054204A1
WO2001054204A1 PCT/SE2001/000072 SE0100072W WO0154204A1 WO 2001054204 A1 WO2001054204 A1 WO 2001054204A1 SE 0100072 W SE0100072 W SE 0100072W WO 0154204 A1 WO0154204 A1 WO 0154204A1
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Prior art keywords
layer
semiconductor
contact layer
doped
dopants
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PCT/SE2001/000072
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English (en)
Inventor
Johan Hammersberg
Olof Hjortstam
Mark Irwin
Jan Isberg
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Abb Ab
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Priority to AU2001228975A priority Critical patent/AU2001228975A1/en
Publication of WO2001054204A1 publication Critical patent/WO2001054204A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H01L29/16—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only elements of Group IV of the Periodic Table
    • H01L29/1602—Diamond
    • 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
    • H01L21/0405—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 semiconducting carbon, e.g. diamond, diamond-like carbon
    • H01L21/041—Making n- or p-doped regions
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H01L29/16—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only elements of Group IV of the Periodic Table
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H01L29/16—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only elements of Group IV of the Periodic Table
    • H01L29/1608—Silicon carbide
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H01L29/16—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only elements of Group IV of the Periodic Table
    • H01L29/161—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only elements of Group IV of the Periodic Table including two or more of the elements provided for in group H01L29/16, e.g. alloys
    • H01L29/165—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only elements of Group IV of the Periodic Table including two or more of the elements provided for in group H01L29/16, e.g. alloys in different semiconductor regions, e.g. heterojunctions
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/40—Electrodes ; Multistep manufacturing processes therefor
    • H01L29/43—Electrodes ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H01L29/47—Schottky barrier electrodes
    • 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
    • H01L31/0248—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 characterised by their semiconductor bodies
    • H01L31/0256—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 characterised by their semiconductor bodies characterised by the material
    • H01L31/0264—Inorganic materials
    • H01L31/028—Inorganic materials including, apart from doping material or other impurities, only elements of Group IV of the Periodic Table
    • 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
    • H01L31/08—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 in which radiation controls flow of current through the device, e.g. photoresistors
    • H01L31/10—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 in which radiation controls flow of current through the device, e.g. photoresistors characterised by potential barriers, e.g. phototransistors
    • H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
    • H01L31/102—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier
    • H01L31/108—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier the potential barrier being of the Schottky type

Definitions

  • the present invention relates to a semiconductor device comprising a first semiconductor layer doped according to either a) n-type or b) p-type and a metal layer forming a contact thereto.
  • the present invention relates to all types of semiconductor devices having a metal layer forming a contact to a doped semiconductor layer.
  • semiconductor devices may normally assume either a blocking state, in which the leakage current therethrough should be as low as possible, or a con- ducting state, in which the power losses generated through the current through the device should be as low as possible.
  • the features of the contacts of such a semiconductor device are essential for obtaining this object.
  • the present invention is in particular, but not exclusively, directed to semiconductor devices in which it is very important that such a contact has two active functions, namely a blocking function in a blocking state of the device and a low ohmic function in the conducting on-state of the device.
  • these two functions are solved separately with two types of contacts, namely a blocking Schottky- contact and a low resistance ohmic contact.
  • ohmic contacts require a very high concentration of thermally activated dopants in said semiconductor layer close to the contact layer, which is not achievable for all types of semi- conductor materials, such as for instance diamond. This fact will make it difficult to produce semiconductor devices made of such materials having excellent properties in said two states also from the contacting point of view with an acceptable low contri- bution from the contacts to leakage current and conducting losses.
  • Diamond has some properties making it extremely interesting as a material in a device for high power applications, one of which is the very high breakdown field strength, which means that the number of devices to be connected in series for holding a volt- age of a certain magnitude may be reduced considerably with respect to devices of other known materials involving important cost reduction even if such a device itself would be much more expensive than the prior art devices, which for the rest is not an evident fact.
  • Other interesting properties of diamond is a very high thermal conductivity and high charge mobility.
  • the object of the present invention is to provide a semiconductor device of the type defined in the introduction having in some respects discussed above an improved function of the contacts thereof with respect to other such devices and making it possible to obtain a contact with a blocking function in a blocking state of the device and a low ohmic function in a conducting state of the device for in particular wide band gap semiconductor materials, such as diamond.
  • This object is according to the present invention obtained by providing such a semiconductor device, in which the semiconductor layer is doped by dopants assuming such deep energy levels in the semiconductor material of said layer that the majority thereof will not be thermally activated at working temperature, the contact layer is of a metal having a work function being for a) substantially as high as or higher than the electron affinity of said semiconductor layer and for b) substantially as high as or lower than the sum of on one hand the band gap between the conduction band and the valence band and on the other the electron affinity of said semiconductor material, and the device comprises an irradiation source adapted to emit radiation of an energy being high enough for activating said dopants and thereby controlling the barrier against charge transport between the contact layer and the semiconductor layer through irradiation of the region of the semiconductor layer closest to the contact layer.
  • the active layers in question may hold a very high voltage when not irradiated thanks to the high breakdown field strength of diamond, but conduct a high current with a low on-state voltage and thereby low losses when irradiated.
  • the problem with a contact having two active functions - a blocking function in the dark off-state and low ohmic function in the on-state activated by irradiation - are not solved there.
  • this is done by combining these features with an adaption of the work function of the metal used for the contact layer to the physical properties of electron affinity and/or band gap and electron affinity of the semiconductor material in question, i.e. by selecting a metal having an appropriate work function.
  • the Fermi-level of the metal will be on substantially the same energy level as the conduction band of the n-type semiconductor layer (for a) and the valence band of a p-doped semiconductor layer (for b).
  • a potential barrier will be formed next to the metal-semiconductor interface due to electron transfer from the metal to the semiconductor on the n- type surface and conversely on the p-type surface. The height of this potential barrier will be given by the energy difference between the conduction band and the Fermi-level deep into the semiconductor material.
  • the potential barrier will be higher. Since the potential barrier and the metal-semiconductor interface is given by the free charge density and the Fermi-level in the semiconductor it will be possible to adjust the potential barrier by using irradiation activation of said dopants located on deep energy levels. Accordingly, said barrier will result in a blocking function of the contact when the semiconductor material next thereto is not irradiated and a low ohmic function when the region in question of the semiconductor material is irradiated, preferably by light.
  • a barrier height around 1 eV will lead to a contact having blocking properties and a barrier height below 0.3 eV would result in low losses of the contact in the forward conducting case, and the concentration of said deep energy level dopants and the intensity of the irradiation source should be selected so as to achieve this.
  • the metal of the contact layer has a work function being for a) substantially higher than the electron affinity of the material of the semiconductor layer and for b) substantially lower than said sum for forming a Schottky-barrier at the interface between the contact layer and the semiconductor layer.
  • the leakage current will be further reduced by such a Schottky- barrier.
  • the height of the Schottky-barrier will be independent of the irradiation by the irradiation source, but the width of the Schottky-barrier can be varied by irradiation.
  • the irradiation of the deep levels in question will have the same effect as a thermally activated doping and the Schottky-barrier width will de- crease as the illumination increases. If the Schottky-barrier is thin enough the charges might tunnel through the barrier in the same way as in a conventional ohmic Schottky tunnelling contact, and this behaviour has to be obtained in the on-state of the device.
  • the blocking function will be improved when the height of the Schottky-barrier is increased, but this will then also result in a wider barrier at a given irradiation intensity. Accordingly it would mostly be appropriate to use a metal resulting in a Schottky-barrier being not much higher than a minimum barrier necessary for obtaining an acceptably good blocking function, and this would typically mean that the Schottky- barrier at the interface between the contact layer and the semiconductor layer should be at least 0.6 eV.
  • the device comprises means promoting tunnelling of charge carriers through said Schottky-barrier when said region of the semiconductor layer is irradiated. This will make it possible to be able to tunnel through a wider barrier than otherwise improving the tunnel probability for a barrier of a certain width, i.e. a certain intensity of the irradiation source, or reducing the required inten- sity of the irradiation source while maintaining the tunnel probability.
  • said tunnelling promoting means is formed by defects introduced close to the contact layer.
  • the introduction of such defects in the Schottky-barrier will increase the tunnelling probability, since the charge carriers may "jump" from one defect level to another defect level within the barrier and thereby come through the barrier, so that they will be able to tunnel through a wider barrier resulting in the options just mentioned.
  • this may be obtained by arranging a third thin layer between said semiconductor layer and the contact layer, which is of a material introducing said defects for promoting tunnelling of charge carriers between the contact layer and the semiconductor layer, and such a layer may in the case of diamond as said semiconductor material be TiC, which is also transparent for the irradiation to be used then. It would also be possible to form the defects by radiation damage of regions of the semiconductor layer next to the contact layer.
  • said semiconductor material is a wide band gap material, i.e. a material having an energy gap between the conduction band and the valence band exceeding 2 eV, and diamond and SiC are of particular interest for such a device thanks to the physical proper- ties thereof.
  • a metal having a work function exceeding 2.9 eV for forming the contact layer which will result in a Schottky-barrier exceeding 0.6 eV.
  • Candidates as metals for such a contact layer are for instance Nd and Sc.
  • a metal having a work function lower than 7.2 eV is to be selected for the contact layer for obtaining a Schottky-barrier height above 0.6 eV.
  • Pt and Pd are candidates as metal for such a contact layer.
  • the device is adapted to switch between a state of conducting current and a state of blocking transport of charge carriers between two terminals of the device upon applying a voltage thereacross, and said irradiation source is adapted to irradiate said region of the semiconductor layer closest to the contact layer when the device is in the conducting state and interrupt such irradiation when it is in the blocking state.
  • the de- vice comprises means for switching between the conducting state and the blocking state by irradiating material layers between said two terminals, which means that not only the properties of the contact, blocking or conducting, is controlled by irradiation, but also the state of the entire device, and it will then be particularly preferred to use the same irradiation source for controlling both the contacts and the other active layers of the device for switching between said two states.
  • the invention also comprises the uses according to the ap- pended use-claims, and the advantages thereof resides in the possibility to use materials as diamond while obtaining good contact functions and the inherent properties of such materials, in particular diamond and SiC.
  • Figs 1 and 2 are very simplified cross-section views of the terminals and the layers located therebetween of two types of switching devices to which the present invention may be ap- plied,
  • Fig 3 is a schematic cross-section view of another type of a semiconductor device, to which the present invention may be applied,
  • Fig 4 is an energy band diagram of a contact metal layer adjacent to a semiconductor layer doped with deep level dopants in the form of donors in a blocking state of a device according to a first preferred embodiment of the invention
  • Fig 5 is a view corresponding to Fig 4 in a conducting state of said device
  • Fig 6 is a view corresponding to Fig 4 for a device according to a second preferred embodiment of the invention.
  • Fig 7 is a view corresponding to Fig 5 for said device according to the second preferred embodiment of the invention.
  • Fig 8 is a view corresponding to Figs 5 and 7 for a device according to a third preferred embodiment of the invention in the conducting state
  • Fig 9 illustrates an energy band diagram of a metal adjacent to a semiconductor layer doped with dopants in the form of acceptors on deep energy levels of a device according to a fourth preferred embodiment of the invention in the blocking state thereof, and
  • Fig 10 is a view corresponding to Fig 9 when said device is in a conducting state.
  • Fig 1 illustrates a semiconductor device having two terminals 1 , 2 for connecting the device to an electric current path.
  • the device has also one first semiconductor layer 3 of diamond doped by dopants assuming such deep energy levels that the majority thereof will not be thermally activated at room temperature, and this means that the activation energy of said dopants should be higher than 0.3 eV.
  • the device comprises another first semiconductor layer 4 of diamond doped according to the same conditions as the first layer 3.
  • a second layer 5 of intrinsic diamond is arranged between the two first layers 3 and 4.
  • the layer 5 has typically a thickness of 3 to 200 ⁇ m, whereas the two doped layers 3, 4 have a thickness of 1 to 20 ⁇ m.
  • a metal contact 6, 7 connects the respective terminal to the diamond layer 3 and 4, respectively.
  • the choice of the material of the metal contact is a very essential feature of the present invention and will be discussed further below.
  • the metal contact has preferably vents of the type illustrated for the embodiment according to Fig 3 for allowing penetration of light from a light source through the metal contact and into the respective first layer 3, 4. It should be mentioned that characteristics of this device and the rest of the devices shown in the Figures having nothing to do with the present invention, such as passivation layers, have been omitted for the sake of clearness.
  • FIG. 2 A device according to another possible type, to which the present invention may be applied, is shown in Fig 2, which differs from that illustrated in Fig 1 by the fact that the two first layers 3, 4 are made thicker and the intrinsic layer 5 is omitted, so that only the two first layers are arranged between the two metal contacts 6, 7.
  • the metal contacts 10 arranged on a first side are laterally displaced with respect to the metal contacts 1 1 arranged on the opposite side of the device and light sources 12 are adapted to illuminate a region under the respective metal contact for activation of dopants occupying deep energy levels there from the opposite side of the device, so that the light source shown to the right in the Figure will activate the acceptors in the layers 3 underneath the anodes through illumination through the intrinsic layer 5, whereas the light source shown to the left will illuminate and activate donors in the layers 4 underneath the cathodes of the device.
  • a voltage source 13 and a load 14 for the circuit, to which the device is connected, are also indicated in this Figure.
  • the acceptors in the layer 3 occupy levels at a considerable distance to the valence band of the diamond lattice, whereas the dopants of the first layer 4, which are assumed to be donors, occupy levels located at a substantial energy distance below the conduction band of the diamond lattice. Said energy distance is preferably above 0.5 eV, so that practically none of these dopants are thermally activated at room temperature.
  • the first layers 3 and 4 will without said illumination have practically no free charge carries for transport between the anode and the cathode and they will act as intrinsic layers, so that the switch is then able to block very high voltages applied thereacross in any direction as long as no charge carriers are injected at the contacts, and the present invention aims at taking care of that issue.
  • a standard Xenon-lamp may be used as said irradiation sources 12, since it has only to deliver light with an energy above said activation energy, which for instance for donors of N is 1 .7 eV, which should be compared with energy needed to lift electrons from the valence band to the conduction band in diamond (5.4 eV). It is illustrated in Fig 4 what is happening when a metal having substantially the same work function ⁇ , i.e. energy distance between the Fermi-level and the vacuum level, as the electron affinity (2.3 eV for diamond), i.e.
  • the energy distance between the conduction band and the vacuum level, of the semiconductor material is selected as material for the contact layer 1 1 next to the layer 4 doped with donors.
  • Candidates for the metal are Cs, Eu and Rd with the work functions 2.14 eV, 2.5 eV and 2.16 eV, respectively.
  • the conduction band will at the interface to the metal be on Fermi-level and then rise into the bulk of the semiconductor layer forming a potential barrier therein due to electron transfer from the metal to the semiconductor.
  • This potential barrier 15 has for diamond typically a height of 1 eV.
  • the dopants 16 located on deep energy levels are here not activated. Accordingly, a potential barrier having a blocking function and preventing injection of electrons from the metal is formed in this way.
  • Fig 5 It is illustrated in Fig 5 what is happening when the region of the semiconductor layer 4 closest to the metal contact is illuminated with light having an energy sufficient to excite electrons of said deep energy level dopants. This will increase the free charge density in the semiconductor and thereby reduce the gap between the conduction band 17 and the Fermi-level 18 and thereby the height of said barrier. The lowering of the barrier to about 0.3 eV will result in an acceptably low resistance and thereby voltage drop and power losses at the contact in question in the conducting state of the device.
  • the blocking capacity of a device having a contact with the properties illustrated in Figs 4 and 5 sometimes are acceptable, it will in some cases be desired to reduce the leakage current in the blocking state further, and this is done by selecting a metal for the contact layer with a work function ⁇ being substantially higher than the electron affinity ⁇ of the semiconductor material.
  • a metal for the contact layer with a work function ⁇ being substantially higher than the electron affinity ⁇ of the semiconductor material.
  • the conduction band 17 of the semiconductor material will directly at the interface form a potential barrier of Schottky-type preventing injections of electrons from the metal.
  • Fig 8 differs from that according to Figs 6 and 7 by the fact that defects 20 promoting tunnelling of charge carriers through said Schottky-barrier have been introduced close to the interface 21 between the metal and the semiconductor material. This may be done by arranging a very thin layer of for instance TiC at said interface 21 .
  • An alternative is to expose the region of the semiconductor layer closest to the contact layer for radiation for damaging it and introduce defects thereby.
  • a possible defect layer 25 of TiC is schematically indicated in Fig 8.
  • the inventional idea is of course also applicable to a contact between a metal contact layer and a semiconductor layer doped according to p-type, i.e. with acceptors, and the work function of the metal is in such a case to be compared with the sum of on one hand the band gap between the conduction band a the valence band and on the other the electron affinity of the semicon- ductor material, and it has to be substantially as high as or lower than that sum.
  • Figs 9 and 10 It is schematically illustrated in Figs 9 and 10 what is happening on the p-side, accordingly close to the interface between the contact layer 10 and the layer 3 in the device according to Fig 3, in the blocking state and in the con- ducting state of the device when selecting a metal for said contact layer having a work function being substantially the same as said sum. It is illustrated how the valence band 22 will be at the Fermi-level 23 of diamond at the interface 21 and at the Fermi- level of the metal there. However, a barrier will be formed in the direction of the bulk being approximately 1 .0 eV.
  • 3.2 eV Nd and Sc are candidates for the embodiment shown in Figs 4 and 5 where the work function is 3.0-3.5 eV and Ag and Al having both a work function of 4.3 eV are candidates for the embodiment shown in Figs 6-8 where the work function shall exceed 3.8 eV, while Pt, Pd and Ni having work functions of 5.63 eV, 5.6 eV and 5.2 eV, respectively, are candidates for the embodiment according to Figs 6-8 with a p-type semiconductor layer where the work function shall be lower than 5.8 eV.
  • Pt and Pd may be used for p-type dopants and the embodiment according to Figs 6-8.
  • a device according to the invention is preferably adapted to hold voltages above 1 kV, especially above 10 kV, in absence of irradiation through said source.
  • This device may advantageously be used in a high voltage converter operating at a voltage in the region of 10 kV-500 kV.
  • semiconductor material as used in the claims is to be interpreted broadly and also include an insulator as diamond being doped with deep level dopants, which may be activated by irradiation.
  • irradiation does not necessarily have to be illumination, but it is also conceivable to use for instance beams of electrons.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
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  • Condensed Matter Physics & Semiconductors (AREA)
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  • Manufacturing & Machinery (AREA)
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  • Inorganic Chemistry (AREA)
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Abstract

Dans un dispositif à semi-conducteur comprenant une première couche de semi-conducteurs (4) dopée par des dopants supportant des niveaux d'énergie dans le matériau semi-conducteur de ladite couche, tels que la majorité de ceux-ci ne sera pas thermiquement activée à température d'emploi; une couche de contact (11) métallique possédant une fonction de travail (ζ) conçue pour un dopage de type N sensiblement aussi élevé ou supérieur à l'affinité du matériau semi-conducteur aux électrons (ψ) et conçue pour un dopage de type P sensiblement aussi élevé ou inférieur d'une part, à la somme de l'espace de bande interdite entre la bande de conduction et la bande de valence et d'autre part, à l'affinité aux électrons dudit matériau semi-conducteur. Le dispositif comprend une source de rayonnement conçue pour émettre des rayonnements possédant une énergie suffisamment élevée pour activer lesdits dopants et ainsi commander la barrière contre le transport de charge entre la couche de contact et la couche de semi-conducteurs.
PCT/SE2001/000072 2000-01-17 2001-01-17 Dispositif a semi-conducteur WO2001054204A1 (fr)

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SE0000115A SE0000115D0 (sv) 2000-01-17 2000-01-17 A semiconductor device

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010012739A1 (fr) * 2008-07-29 2010-02-04 Commissariat A L'energie Atomique Substrat de type semi-conducteur sur isolant a couches de diamant intrinseque et dope
CN102956740A (zh) * 2011-08-22 2013-03-06 西门子公司 检测器元件、辐射检测器和具有这样的检测器元件的医疗设备和用于制造检测器元件的方法

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