WO2011018984A1 - Photoelectric conversion device - Google Patents

Photoelectric conversion device Download PDF

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Publication number
WO2011018984A1
WO2011018984A1 PCT/JP2010/063335 JP2010063335W WO2011018984A1 WO 2011018984 A1 WO2011018984 A1 WO 2011018984A1 JP 2010063335 W JP2010063335 W JP 2010063335W WO 2011018984 A1 WO2011018984 A1 WO 2011018984A1
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layer
photoelectric conversion
conversion device
photosensitizing
inn
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PCT/JP2010/063335
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French (fr)
Japanese (ja)
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吉川　明彦
善博 石谷
一秀 草部
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国立大学法人千葉大学
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Priority to JP2011526725A priority Critical patent/JP5424503B2/en
Publication of WO2011018984A1 publication Critical patent/WO2011018984A1/en

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    • 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
    • H01L31/105—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier the potential barrier being of the PIN type
    • 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
    • H01L31/0304—Inorganic materials including, apart from doping materials or other impurities, only AIIIBV compounds
    • H01L31/03044—Inorganic materials including, apart from doping materials or other impurities, only AIIIBV compounds comprising a nitride compounds, e.g. GaN
    • 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
    • H01L31/0352—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 their shape or by the shapes, relative sizes or disposition of the semiconductor regions
    • H01L31/035209—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 their shape or by the shapes, relative sizes or disposition of the semiconductor regions comprising a quantum structures
    • 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
    • H01L31/04—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 adapted as photovoltaic [PV] conversion devices
    • H01L31/06—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 adapted as photovoltaic [PV] conversion devices characterised by potential barriers
    • H01L31/075—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 adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PIN type, e.g. amorphous silicon PIN solar cells
    • H01L31/077—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 adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PIN type, e.g. amorphous silicon PIN solar cells the devices comprising monocrystalline or polycrystalline materials
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/544—Solar cells from Group III-V materials
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/547—Monocrystalline silicon PV cells

Definitions

  • the present invention relates to a photoelectric conversion device suitable for infrared light detection and switching.
  • the infrared detection element is made of mercury cadmium telluride (HgCdTe) based photoconductive material.
  • HgCdTe mercury cadmium telluride
  • HgCdTe is very difficult to form such as crystal growth.
  • HgCdTe is highly toxic, its use is problematic from the viewpoint of environmental impact.
  • an infrared detection element having a semiconductor quantum well structure is known.
  • light absorption uses an intraband transition process in a quantum well, that is, an intersubband transition.
  • FIG. 10 is a block diagram showing a configuration of a photoelectric conversion device 100 using an in-band transition process as an example, and includes a barrier layer 102, a quantum well layer 103 formed on the barrier layer 102, and the quantum well layer. And a barrier layer 104 formed on the substrate 103, and these are formed as a basic structure of an infrared detection device by a known semiconductor manufacturing technique or the like.
  • An infrared detector may be configured by a multi-quantity well structure in which a plurality of basic structures are stacked.
  • the infrared incident surface is the upper surface of the second barrier layer 104. In other words, infrared rays are incident on the photoelectric conversion device 100 from the z direction in FIG.
  • FIG. 11 is a conceptual diagram showing a band lineup of the barrier layers 102 and 104 and the quantum well layer 103.
  • the quantum well layer 103 is sandwiched between the barrier layers 102 and 104, and the CBM indicates the bottom of the conduction band, and the energy increases from bottom to top in the figure. It has become.
  • the electron ground level Ec in the well layer 103 is formed at the energy position indicated by the dotted line in the figure.
  • the in-band transition process includes an intersubband transition in which electrons in the quantum well layer 103 transition from the ground level Ec to the excited level.
  • this excitation level has an energy higher than that of the conduction band bottom CBM of the barrier layers 103, 104, electrons are transferred to the barrier layers 103, 104 by phonon scattering, an externally applied electric field, or an inherent electric field. Can be taken out. Through such a process, photoelectric conversion is performed, and infrared detection becomes possible.
  • the intraband transition process is required to satisfy the following polarization selection rule.
  • an in-band transition process is allowed only for the polarization component in the z direction.
  • This is the polarization selection rule.
  • the polarization of the infrared light is directed in the xy plane. That is, when the detected infrared light is incident on the photoelectric conversion device 100 perpendicularly, the polarization of the incident infrared light is also in the xy direction with respect to the quantum well layer 103.
  • the intra-band transition process described above is forbidden by the polarization selection rule. For this reason, in the in-band transition transition, the photoelectric conversion apparatus 100 cannot detect infrared rays incident vertically.
  • the s-polarization component does not include the z-direction polarization component with respect to the quantum well layer 103, but the p-polarization component includes the z-direction polarization component, so that an in-band transition process is allowed. Is done.
  • such oblique incidence of infrared rays reduces the amount of infrared rays applied to the photoelectric conversion device 100, and thus has a problem of reducing detection sensitivity.
  • the present invention has been made in view of such circumstances, and an object thereof is to provide a photoelectric conversion device having high conversion efficiency in infrared detection using an in-band transition process.
  • the photoelectric conversion device is formed on a first conductive layer of a first conductivity type, a photosensitizing layer formed on the first conductive layer, and the photosensitizing layer.
  • a photoelectric conversion device comprising a second conductive layer of the second conductivity type and a deflecting unit formed on the second conductive layer, wherein the photosensitizing layer is a photoelectric conversion by an in-band transition process. I do.
  • the first conductive layer has a first band gap energy
  • the second conductive layer has a second band gap energy
  • the photosensitizing layer has a first band gap energy.
  • the third band gap energy may be smaller than the first and second band gap energies.
  • the deflection unit may have an uneven shape on the surface.
  • the deflecting unit may be composed of fine particles.
  • the deflecting unit may be configured to surround the first conductive layer, the photosensitizing layer, and the second conductive layer.
  • the photosensitizing layer has the photoelectric conversion layer generated by the intraband transition process for carriers generated by light absorption higher than the third band gap energy. Conversion may be performed.
  • the photoelectric conversion device includes a first In x Ga y Al 1-xy N layer having a first conductivity type, and the first In x Ga y Al 1-xy N layer.
  • -Y is a photoelectric conversion device including a deflection unit formed on the N layer, wherein the ranges of x and y are 0 ⁇ x, y ⁇ 1, and the photosensitizing layer has a layer thickness of 2 It includes the following InN molecular layer, the carrier in the photosensitizing layer, at least one of said first 1In x Ga y Al 1-x -y N layer and said second 2In x Ga y Al 1-x -y N layer In addition, it is movable by an in-band transition process.
  • the deflection unit may have an uneven shape on the surface.
  • the deflecting unit may be composed of fine particles.
  • the xy N layer may be enclosed.
  • the photosensitizing layer has the intra-band transition with respect to carriers generated by light absorption having energy higher than the effective band gap energy of the photosensitizing layer. You may perform the said photoelectric conversion by a process.
  • FIG. 1 is a block diagram showing a configuration example of a photoelectric conversion apparatus 10 according to the first embodiment of the present invention.
  • a photoelectric conversion device 10 is formed on an n-type gallium nitride (hereinafter referred to as n-GaN) layer 12, a photosensitizing layer 13 formed on the n-GaN layer 12, and a photosensitizing layer 13.
  • the p-type gallium nitride (hereinafter referred to as p-GaN) layer 14 and the deflecting portion 15 formed on the p-GaN layer 14 are configured.
  • the photosensitizing layer 13 has an indium nitride (InN) quantum well structure described below, and is used for photoelectric conversion by an in-band transition process.
  • the n-GaN layer 12 is used to transport electrons excited by the intraband transition process.
  • the p-GaN layer 14 is used to transport holes excited by the intraband transition process. Accordingly, the resistivity and the layer thickness of the n-GaN layer 12 and the p-GaN layer 14 are each suitably adjusted in order to efficiently transport carriers.
  • the deflecting unit 15 deflects the propagation direction of incident infrared rays, and as a result, controls the polarization of incident infrared rays.
  • InN is formed on GaN by a known semiconductor manufacturing technique or the like.
  • InN and GaN have a lattice mismatch of about 11%, so that high-density lattice defects are introduced during crystal growth. This lattice defect significantly deteriorates the photoelectric conversion efficiency.
  • the inventors have found that the upper limit of the film thickness that allows InN to retain elastic deformation without introducing lattice defects and coherently grow with respect to GaN, that is, the critical film thickness, is a bimolecular layer (2ML). .
  • FIG. 2 is a block diagram showing the photosensitizing layer 13 according to this embodiment.
  • the quantum well structure composed of the quantum well layer made of the ultrathin film InN and the barrier layer made of the GaN layer corresponds to the photosensitizing layer 13 according to the present embodiment.
  • the growth temperature of InN was limited to about 600 ° C. or less in the molecular beam epitaxy (MBE) method, for example, the inventors found that the ultra-thin film InN can grow at 600 ° C. or more. It was. By this high temperature growth, the crystallinity of the ultra-thin film InN is dramatically improved. As a result, the photosensitizing layer 13 exhibits high photoelectric conversion efficiency (internal quantum efficiency). Thus, unlike ordinary bulk InN, ultrathin film InN exhibits specific physical properties.
  • MBE molecular beam epitaxy
  • FIG. 3 is a block diagram showing the photosensitizing layer 13 composed of the fractional layer InN.
  • the fractional layer InN means that the surface coverage is 1 or less.
  • the 0.5 molecular layer is a one-layer thickness and the surface coverage is 50%. This corresponds to an island structure, that is, a quantum disk structure.
  • FIG. 4 is a block diagram showing the photosensitizing layer 13 composed of an ultrathin film InN formed on the surface wavy structure of GaN.
  • the ultra-thin film InN when an ultra-thin film InN is formed on the surface undulation structure of GaN, the ultra-thin film InN also shows a similar surface undulation structure, reflecting this surface undulation structure.
  • the ultra-thin film InN is formed by a self-ordered and self-stop forming process having high structural integrity for each terrace of each atomic layer step.
  • the photosensitizing layer 13 may have a multi-quantum well structure made of not only a single layer but also a multilayer ultra-thin film InN. According to this configuration, the amount of light to be absorbed increases as the number of quantum well layers of the InN ultrathin film increases, so that the photoelectric conversion efficiency can be further enhanced.
  • FIG. 5 is a conceptual diagram showing a band lineup of GaN and InN.
  • a quantum well layer made of ultra-thin InN is sandwiched between GaN barrier layers, and CBM and VBM indicate the bottom of the conduction band and the top of the valence band, respectively. It becomes the arrangement where the energy becomes higher toward.
  • the band gap energies of InN and GaN are about 0.65 eV and 3.4 eV, respectively, the conduction band offset is about 2 eV, and the valence band offset is about 0.75 eV.
  • the carriers are transferred from the InN layer to the GaN layer as a current by the in-band transition process by infrared absorption. It cannot be taken out. That is, infrared rays cannot be detected.
  • the effective band gap energy (difference between Ec and Ev) of the ultrathin film InN is shifted from 0.65 eV.
  • the effective band gap energy is always 500 meV lower than the band gap energy of GaN
  • the effective band gap energy is always 200 meV lower than the band gap energy of GaN.
  • the difference between the effective band gap energy and the band gap energy of GaN is automatically controlled to about 500 meV for the bimolecular layer and about 200 meV for the single molecular layer.
  • the effective band gap energy is easily and precisely determined by the structural integrity of the ultra-thin film InN.
  • the deflecting portion 15 which is the second important point of the present invention will be described.
  • the incident infrared light polarization includes a component in the stacking direction of the photosensitizing layer 13.
  • the deflecting unit 15 deflects the propagation direction of the incident infrared rays, and the incident infrared rays have a p-polarized component. It controls suitably.
  • the polarization selection rule is satisfied because the p-polarized component with respect to the photosensitizing layer 13 is expressed in the same manner as the oblique incidence arrangement shown in FIG.
  • the deflecting unit 15 is configured by a non-uniform refractive index distribution.
  • this inhomogeneous refractive index corresponds to the fact that the refractive index varies internally in the case of a flat film structure, while it corresponds to a non-flat film structure in the case of a medium having a uniform refractive index.
  • FIG. 6 is a block diagram showing the configuration of the photoelectric conversion apparatus 20 according to the first embodiment of the present invention.
  • the photoelectric conversion device 20 is formed on an n-type gallium nitride (n-GaN) layer 22, a photosensitizing layer 23 formed on the n-GaN layer 22, and the photosensitizing layer 23.
  • the p-type gallium nitride (p-GaN) layer 24 and the deflection unit 25 formed on the p-GaN layer 24 are configured.
  • the deflecting unit 25 has a concavo-convex structure on the infrared incident surface.
  • the concavo-convex structure present on the incident surface of the deflecting unit 25 deflects the propagation direction of the infrared by reflection or refraction.
  • the dimensions of the unevenness, step and interval of the unevenness are approximately the same as or larger than the wavelength of incident infrared rays.
  • the effective incident direction deviates from the vertical direction and can be regarded as the same as the oblique incident.
  • the polarization selection rule for allowing the in-band transition process is satisfied. As a result, infrared rays can be detected.
  • the surface reflectance is suppressed by the uneven structure present on the incident surface of the deflecting unit 25 compared to a flat case, so that effective light capturing efficiency is improved. improves.
  • the concavo-convex structure of the deflecting portion 25 is formed by faceting by etching or selective growth of a nitride semiconductor formed by a known semiconductor manufacturing technique or the like. In addition to this, it is formed by etching a material formed by a known film forming technique or the like.
  • This dielectric is made of, for example, zinc oxide (ZnO), indium tin oxide (ITO), silicon dioxide (SiO 2 ), titanium dioxide (TiO 2 ), or zirconium dioxide (ZrO 2 ).
  • FIG. 7 is a block diagram showing a configuration of a photoelectric conversion apparatus 30 according to the second embodiment of the present invention.
  • the photoelectric conversion device 30 is formed on an n-type gallium nitride (n-GaN) layer 32, a photosensitizing layer 33 formed on the n-GaN layer 32, and the photosensitizing layer 33.
  • the p-type gallium nitride (p-GaN) layer 34 and the deflecting portion 35 formed on the p-GaN layer 34 are configured.
  • the deflection unit 35 is configured by a fine particle structure.
  • the fine particle structure constituting the deflection unit 35 deflects the propagation direction of the infrared rays by reflection or refraction. For this reason, the particle diameter of the fine particles is approximately the same as or larger than the wavelength of the incident infrared rays. As a result, the effective incident direction deviates from the vertical direction and can be regarded as the same as the oblique incident. In other words, since the p-polarized light component for the photosensitizing layer 33 appears, the polarization selection rule for allowing the in-band transition process is satisfied. As a result, infrared rays can be detected.
  • the surface reflectance is suppressed by the surface structure existing on the incident surface of the deflecting portion 35 as compared with a flat case, so that effective light capturing efficiency is improved. improves.
  • the fine particle structure of the deflection unit 35 is formed by etching or selective growth of a nitride semiconductor formed by a known semiconductor manufacturing technique or the like.
  • microspheres formed by a known manufacturing technique or the like are formed by coating the p-GaN layer 34.
  • the microspheres are made of, for example, zinc oxide (ZnO), indium tin oxide (ITO), silicon dioxide (SiO 2 ), titanium dioxide (TiO 2 ), or zirconium dioxide (ZrO 2 ).
  • FIG. 8 is a block diagram showing a configuration of a photoelectric conversion apparatus 40 according to the third embodiment of the present invention.
  • a photoelectric conversion device 40 is formed on an n-type gallium nitride (n-GaN) layer 42, a photosensitizing layer 43 formed on the n-GaN layer 42, and the photosensitizing layer 43.
  • n-GaN gallium nitride
  • p-GaN p-type gallium nitride
  • p-GaN layer 44, an n-GaN layer 42, an InN photosensitizing layer 43, and a deflection unit 45 formed so as to surround the p-GaN layer 44 are configured.
  • the deflecting unit 45 may have a concavo-convex structure on the surface or a fine particle structure.
  • the deflecting unit 45 When infrared rays are incident on the deflecting unit 45, the deflecting unit 45 deflects the propagation direction of the infrared rays incident from all directions by refraction. As a result, a p-polarized component for the photosensitizing layer 43 appears, so that the polarization selection rule for allowing the in-band transition process is satisfied. As a result, infrared rays can be detected. Furthermore, since the infrared rays from all directions can be incident on the deflecting unit 45, the effective light receiving area is increased and the light capturing efficiency is improved.
  • the deflection unit 45 is formed by a nitride semiconductor film forming process formed by a known semiconductor manufacturing technique or the like, or an etching process. In addition to this, it is formed of a material formed by a known manufacturing technique or the like.
  • This dielectric is made of, for example, zinc oxide (ZnO), indium tin oxide (ITO), silicon dioxide (SiO 2 ), titanium dioxide (TiO 2 ), or zirconium dioxide (ZrO 2 ).
  • infrared detection using an in-band transition process has been described as the photoelectric conversion device according to the present invention.
  • infrared switching that is, light-light modulation, in which the intraband transition process is controlled by external light will be described.
  • the configuration of the photoelectric conversion device according to the present invention is the same as that of the first embodiment, the operation principle of infrared light-light modulation will be described with reference to FIGS.
  • FIG. 9 is a conceptual diagram showing a band lineup of GaN and InN.
  • a quantum well layer made of ultra-thin InN is sandwiched between GaN barrier layers, and CBM and VBM indicate the bottom of the conduction band and the top of the valence band, respectively. It becomes the arrangement where the energy becomes higher toward.
  • the quantum levels Ec and Ev of electrons and holes in the quantum well are formed at the energy positions indicated by dotted lines in the figure, and the effective band gap energy of the ultrathin film InN corresponds to the difference between Ec and Ev.
  • the effective band gap energy of the ultra-thin film InN is greatly different from about 0.65 eV which is the band gap energy of normal InN.
  • the effective band gap energy is always the band of GaN. 500 meV lower than the gap energy, and in the single molecular layer InN, the effective band gap energy is always 200 meV lower than the band gap energy of GaN. Therefore, the effective band gap energy corresponds to 2.9 eV or more.
  • the photoelectric conversion device 10 can perform infrared light switching, that is, light-light modulation, with external light having an energy of 2.9 eV or more.
  • the present invention is not limited to this.
  • indium gallium aluminum nitride hereinafter, In x Ga y Al 1-1) is used.
  • the range of xy N, x, and y can be configured by 0 ⁇ x, y ⁇ 1).
  • the photoelectric conversion device according to the present invention can be used for a detector and a modulator corresponding to mid-infrared light, or a photoelectric conversion device suitable for a photosensitization function in a solar cell.

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Abstract

Disclosed is a photoelectric conversion device which detects, by means of intraband transition, infrared light inputted perpendicularly. The photoelectric conversion device is provided with: a first conductive layer composed of a first conductivity type material; a photosensitizing layer formed on the first conductive layer; a second conductive layer, which is formed on the photosensitizing layer and is composed of a second conductivity type material; and a deflecting section formed on the second conductive layer. The photosensitizing layer performs photoelectric conversion by means of intraband transition process. In such case, the deflecting section may be configured so as to surround the first conductive layer, the photosensitizing layer, and the second conductive layer.

Description

光電変換装置Photoelectric conversion device
　本発明は、赤外光の検出およびスイッチングに好適な光電変換装置に関する。 The present invention relates to a photoelectric conversion device suitable for infrared light detection and switching.
　従来、赤外線検出素子は、テルル化水銀カドミニウム（ＨｇＣｄＴｅ）系光伝導材料によって構成されている。しかし、ＨｇＣｄＴｅは、結晶成長などの形成プロセスが非常に困難である。さらに、ＨｇＣｄＴｅは毒性が強いため、環境負荷という観点からも、その使用については問題がある。 Conventionally, the infrared detection element is made of mercury cadmium telluride (HgCdTe) based photoconductive material. However, HgCdTe is very difficult to form such as crystal growth. Furthermore, since HgCdTe is highly toxic, its use is problematic from the viewpoint of environmental impact.
　一方で、半導体量子井戸構造で構成される赤外線検出素子が知られている。例えば、特許文献１に記載の赤外線検出器では、光吸収は、量子井戸中のバンド内遷移過程、すなわち、サブバンド間遷移を利用している。 On the other hand, an infrared detection element having a semiconductor quantum well structure is known. For example, in the infrared detector described in Patent Document 1, light absorption uses an intraband transition process in a quantum well, that is, an intersubband transition.
　次に、半導体量子井戸構造を備える赤外線検出素子の構成について、図１０および図１１を参照して説明する。図１０は一例として、バンド内遷移過程を利用する光電変換装置１００の構成を示すブロック図であり、障壁層１０２と、前記障壁層１０２上に形成される量子井戸層１０３と、前記量子井戸層１０３上に形成される障壁層１０４と、を備える構成からなり、これらが周知の半導体製造技術などによって、赤外線検出装置の基本構造として形成されている。この基本構造を、複数積層されなる多重量井戸構造によって、赤外線検出器を構成することもある。赤外線の入射面は、第２の障壁層１０４上面であり、言い換えれば、赤外線は、図１０のｚ方向から光電変換装置１００へ向けて入射される。 Next, the configuration of an infrared detection element having a semiconductor quantum well structure will be described with reference to FIGS. FIG. 10 is a block diagram showing a configuration of a photoelectric conversion device 100 using an in-band transition process as an example, and includes a barrier layer 102, a quantum well layer 103 formed on the barrier layer 102, and the quantum well layer. And a barrier layer 104 formed on the substrate 103, and these are formed as a basic structure of an infrared detection device by a known semiconductor manufacturing technique or the like. An infrared detector may be configured by a multi-quantity well structure in which a plurality of basic structures are stacked. The infrared incident surface is the upper surface of the second barrier layer 104. In other words, infrared rays are incident on the photoelectric conversion device 100 from the z direction in FIG.
　図１１は、障壁層１０２，１０４と量子井戸層１０３の、バンドラインナップを示した概念図である。図１１において、図１０と同様に、量子井戸層１０３が、障壁層１０２，１０４によって挟まれており、ＣＢＭは、伝導帯底部を示し、図中下から上に向かってエネルギーが高くなる配置となっている。井戸層１０３における電子の基底準位Ｅｃは、図中点線のエネルギー位置に形成される。
バンド内遷移過程とは、量子井戸層１０３の電子が、基底準位Ｅｃから励起準位へ遷移するサブバンド間遷移を含む。この励起準位が、障壁層１０３，１０４の伝導帯底部ＣＢＭよりも高いエネルギーであれば、フォノン散乱、外部より印加された電界、または内在する電界のいずれかによって、電子を障壁層１０３，１０４へと取り出せる。このような過程によって光電変換を行い、赤外線の検出が可能になる。 FIG. 11 is a conceptual diagram showing a band lineup of the barrier layers 102 and 104 and the quantum well layer 103. In FIG. 11, similarly to FIG. 10, the quantum well layer 103 is sandwiched between the barrier layers 102 and 104, and the CBM indicates the bottom of the conduction band, and the energy increases from bottom to top in the figure. It has become. The electron ground level Ec in the well layer 103 is formed at the energy position indicated by the dotted line in the figure.
The in-band transition process includes an intersubband transition in which electrons in the quantum well layer 103 transition from the ground level Ec to the excited level. If this excitation level has an energy higher than that of the conduction band bottom CBM of the barrier layers 103, 104, electrons are transferred to the barrier layers 103, 104 by phonon scattering, an externally applied electric field, or an inherent electric field. Can be taken out. Through such a process, photoelectric conversion is performed, and infrared detection becomes possible.
　バンド内遷移過程には、次に述べる偏光選択則を満足することが要求される。図１０に示すように、量子井戸層１０３の閉じ込め構造がｚ方向である場合、ｚ方向の偏光成分に対してのみ、バンド内遷移過程が許容される。これが、偏光選択則である。
赤外線が、ｚ方向に沿って伝搬するとき、赤外線の偏光はｘｙ面内を向いている。すなわち、検出される赤外線が、光電変換装置１００に対して垂直に入射する場合、量子井戸層１０３に対しても、入射赤外線の偏光はｘｙ方向である。そのため、前記偏光選択則より、上述したバンド内遷移過程は禁制である。このため、バンド内遷移遷移では、光電変換装置１００は、垂直入射する赤外線を検出できない。 The intraband transition process is required to satisfy the following polarization selection rule. As shown in FIG. 10, when the confinement structure of the quantum well layer 103 is in the z direction, an in-band transition process is allowed only for the polarization component in the z direction. This is the polarization selection rule.
When infrared light propagates along the z direction, the polarization of the infrared light is directed in the xy plane. That is, when the detected infrared light is incident on the photoelectric conversion device 100 perpendicularly, the polarization of the incident infrared light is also in the xy direction with respect to the quantum well layer 103. For this reason, the intra-band transition process described above is forbidden by the polarization selection rule. For this reason, in the in-band transition transition, the photoelectric conversion apparatus 100 cannot detect infrared rays incident vertically.
　そこで、バンド内遷移過程を利用するためには、光電変換装置１００に対して、赤外線を斜め上方、すなわち、ｘｚ面内、から入射させる必要がある。この入射配置では、ｓ偏光成分では、量子井戸層１０３に対して、ｚ方向の偏光成分が含まれないが、ｐ偏光成分では、ｚ方向の偏光成分は含まれるため、バンド内遷移過程は許容される。
　しかし、このような赤外線の斜め入射は、赤外線の光電変換装置１００への照射量を低下させるため、検出感度を低減させるという問題がある。 Therefore, in order to use the in-band transition process, it is necessary to make infrared rays incident on the photoelectric conversion device 100 obliquely from above, that is, in the xz plane. In this incident arrangement, the s-polarization component does not include the z-direction polarization component with respect to the quantum well layer 103, but the p-polarization component includes the z-direction polarization component, so that an in-band transition process is allowed. Is done.
However, such oblique incidence of infrared rays reduces the amount of infrared rays applied to the photoelectric conversion device 100, and thus has a problem of reducing detection sensitivity.
特開２００１－４４４８６号公報Japanese Patent Laid-Open No. 2001-44486
　半導体量子井戸構造で構成される赤外線検出素子において、高い光電変換効率を実現するためには、赤外線の垂直入射と、垂直方向の偏光成分を有するという、一見すると相反する２つの条件を同時に満足することが要求される。 In order to realize high photoelectric conversion efficiency in an infrared detection element constituted by a semiconductor quantum well structure, two seemingly contradictory conditions of perpendicular incidence of infrared rays and vertical polarization components are simultaneously satisfied. Is required.
　本発明は、このような事情に鑑みてなされたもので、バンド内遷移過程を利用する赤外線検出において、高い変換効率を有する光電変換装置を提供することを目的とする。 The present invention has been made in view of such circumstances, and an object thereof is to provide a photoelectric conversion device having high conversion efficiency in infrared detection using an in-band transition process.
　本発明の第１態様である光電変換装置は、第１伝導型からなる第１伝導層と、　前記第１伝導層上に形成される光増感層と、前記光増感層上に形成され、第２伝導型からなる第２伝導層と、前記第２伝導層上に形成される偏向部と、を備える光電変換装置であって、前記光増感層は、バンド内遷移過程による光電変換を行う。 The photoelectric conversion device according to the first aspect of the present invention is formed on a first conductive layer of a first conductivity type, a photosensitizing layer formed on the first conductive layer, and the photosensitizing layer. A photoelectric conversion device comprising a second conductive layer of the second conductivity type and a deflecting unit formed on the second conductive layer, wherein the photosensitizing layer is a photoelectric conversion by an in-band transition process. I do.
　本発明の第１態様である光電変換装置では、前記第１伝導層は第１バンドギャップエネルギーを有し、前記第２伝導層は第２バンドギャップエネルギーを有し、前記光増感層は第３バンドギャップエネルギーを有し、前記第３バンドギャップエネルギーは前記第１および前記第２バンドギャップエネルギーよりも小さくてもよい。 In the photoelectric conversion device according to the first aspect of the present invention, the first conductive layer has a first band gap energy, the second conductive layer has a second band gap energy, and the photosensitizing layer has a first band gap energy. The third band gap energy may be smaller than the first and second band gap energies.
　本発明の第１態様である光電変換装置では、前記偏向部は、表面に凹凸形状を有してもよい。 In the photoelectric conversion device according to the first aspect of the present invention, the deflection unit may have an uneven shape on the surface.
　本発明の第１態様である光電変換装置では、前記偏向部は、微粒子によって構成されてもよい。 In the photoelectric conversion device according to the first aspect of the present invention, the deflecting unit may be composed of fine particles.
　本発明の第１態様である光電変換装置では、前記偏向部は、前記第１伝導層と、前記光増感層と、前記第２伝導層と、を囲むように構成されてもよい。 In the photoelectric conversion device according to the first aspect of the present invention, the deflecting unit may be configured to surround the first conductive layer, the photosensitizing layer, and the second conductive layer.
　本発明の第１態様である光電変換装置では、前記光増感層は、前記第３バンドギャップエネルギーよりも高エネルギーの光吸収によって生成されたキャリアに対して、前記バンド内遷移過程による前記光電変換を行ってもよい。 In the photoelectric conversion device according to the first aspect of the present invention, the photosensitizing layer has the photoelectric conversion layer generated by the intraband transition process for carriers generated by light absorption higher than the third band gap energy. Conversion may be performed.
　本発明の第２態様である光電変換装置は、第１伝導型からなる第１ＩｎｘＧａｙＡｌ１－ｘ－ｙＮ層と、前記第１ＩｎｘＧａｙＡｌ１－ｘ－ｙＮ層上に形成される光増感層と、前記光増感層上に形成され、第２伝導型からなる第２ＩｎｘＧａｙＡｌ１－ｘ－ｙＮ層と、前記第２ＩｎｘＧａｙＡｌ１－ｘ－ｙＮ層上に形成される偏向部と、を備える光電変換装置であって、前記ｘおよびｙの範囲は０≦ｘ，ｙ≦１であり、前記光増感層は、層厚が２分子層以下のＩｎＮを含み、前記光増感層におけるキャリアが、前記第１ＩｎｘＧａｙＡｌ１－ｘ－ｙＮ層および前記第２ＩｎｘＧａｙＡｌ１－ｘ－ｙＮ層の少なくともいずれかに、バンド内遷移過程によって移動自在である。 The photoelectric conversion device according to the second aspect of the present invention includes a first In x Ga y Al 1-xy N layer having a first conductivity type, and the first In x Ga y Al 1-xy N layer. A photosensitizing layer to be formed; a second In x Ga y Al 1-xy N layer formed on the photosensitizing layer and having a second conductivity type; and the second In x Ga y Al 1-x. -Y is a photoelectric conversion device including a deflection unit formed on the N layer, wherein the ranges of x and y are 0 ≦ x, y ≦ 1, and the photosensitizing layer has a layer thickness of 2 It includes the following InN molecular layer, the carrier in the photosensitizing layer, at least one of said first 1In x Ga y Al 1-x -y N layer and said second 2In x Ga y Al 1-x -y N layer In addition, it is movable by an in-band transition process.
　本発明の第２態様である光電変換装置では、前記偏向部は、表面に凹凸形状を有してもよい。 In the photoelectric conversion device according to the second aspect of the present invention, the deflection unit may have an uneven shape on the surface.
　本発明の第２態様である光電変換装置では、前記偏向部は、微粒子によって構成されてもよい。 In the photoelectric conversion device according to the second aspect of the present invention, the deflecting unit may be composed of fine particles.
　本発明の第２態様である光電変換装置では、前記偏向部は、前記第１ＩｎｘＧａｙＡｌ１－ｘ－ｙＮ層と、前記光増感層と、前記第２ＩｎｘＧａｙＡｌ１－ｘ－ｙＮ層と、を囲むように構成されてもよい。 In the photoelectric conversion apparatus according to a second aspect of the present invention, the deflection unit, the a first 1In x Ga y Al 1-x -y N layer, said photosensitizer layer, the first 2In x Ga y Al 1- The xy N layer may be enclosed.
　本発明の第２態様である光電変換装置では、前記光増感層は、前記光増感層の実効バンドギャップエネルギーよりも高エネルギーの光吸収によって生成されたキャリアに対して、前記バンド内遷移過程による前記光電変換を行ってもよい。 In the photoelectric conversion device according to the second aspect of the present invention, the photosensitizing layer has the intra-band transition with respect to carriers generated by light absorption having energy higher than the effective band gap energy of the photosensitizing layer. You may perform the said photoelectric conversion by a process.
　以上説明したように、本発明によれば、赤外線を光電変換装置に垂直入射させた場合でも、両井戸構造に対して垂直方向の偏光成分によるバンド内遷移過程が許容される。さらに、入射する赤外線の表面反射が低減されるので、高い光電変換効率を有する光電変換装置を提供することができる。 As described above, according to the present invention, even when infrared rays are vertically incident on the photoelectric conversion device, an in-band transition process by a polarization component in a vertical direction is allowed for both well structures. Furthermore, since surface reflection of incident infrared rays is reduced, a photoelectric conversion device having high photoelectric conversion efficiency can be provided.
本発明の実施形態に係る光電変換装置の構成例を示すブロック図である。It is a block diagram which shows the structural example of the photoelectric conversion apparatus which concerns on embodiment of this invention. 本発明の実施形態に係る光増感層の構成を示すブロック図である。It is a block diagram which shows the structure of the photosensitizing layer which concerns on embodiment of this invention. 本発明の実施形態に係る光増感層の構成を示すブロック図である。It is a block diagram which shows the structure of the photosensitizing layer which concerns on embodiment of this invention. 本発明の実施形態に係る光増感層の構成を示すブロック図である。It is a block diagram which shows the structure of the photosensitizing layer which concerns on embodiment of this invention. ＧａＮとＩｎＮのバンドラインナップを示した概念図である。It is the conceptual diagram which showed the band lineup of GaN and InN. 本発明の実施形態に係る光電変換装置の構成例を示すブロック図である。It is a block diagram which shows the structural example of the photoelectric conversion apparatus which concerns on embodiment of this invention. 本発明の実施形態に係る光電変換装置の構成例を示すブロック図である。It is a block diagram which shows the structural example of the photoelectric conversion apparatus which concerns on embodiment of this invention. 本発明の実施形態に係る光電変換装置の構成例を示すブロック図である。It is a block diagram which shows the structural example of the photoelectric conversion apparatus which concerns on embodiment of this invention. ＧａＮとＩｎＮのバンドラインナップを示した概念図である。It is the conceptual diagram which showed the band lineup of GaN and InN. 従来例におけるバンド内遷移過程による光電変換装置の構成を示すブロック図である。It is a block diagram which shows the structure of the photoelectric conversion apparatus by the transition process in a band in a prior art example. 従来例における光電変換装置のバンド内遷移過程を示す概念図である。It is a conceptual diagram which shows the in-band transition process of the photoelectric conversion apparatus in a prior art example.
　以下、本発明の実施形態につき、図面を参照して説明する。但し、この実施例の記載は、本発明の範囲をそれに限定する趣旨ではなく、単なる説明例に過ぎない。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the description of this example is not intended to limit the scope of the present invention, but is merely an illustrative example.
［第１実施形態］
　図１は、本願発明の第１実施形態に係る光電変換装置１０の構成例を示すブロック図である。図１において、光電変換装置１０は、ｎ型窒化ガリウム（以下、ｎ－ＧａＮ）層１２と、ｎ－ＧａＮ層１２上に形成される光増感層１３と、光増感層１３上に形成されるｐ型窒化ガリウム（以下、ｐ－ＧａＮ）層１４と、ｐ－ＧａＮ層１４上に形成される偏向部１５と、によって構成される。 [First Embodiment]
FIG. 1 is a block diagram showing a configuration example of a photoelectric conversion apparatus 10 according to the first embodiment of the present invention. In FIG. 1, a photoelectric conversion device 10 is formed on an n-type gallium nitride (hereinafter referred to as n-GaN) layer 12, a photosensitizing layer 13 formed on the n-GaN layer 12, and a photosensitizing layer 13. The p-type gallium nitride (hereinafter referred to as p-GaN) layer 14 and the deflecting portion 15 formed on the p-GaN layer 14 are configured.
　光増感層１３は、以下で説明される窒化インジウム（ＩｎＮ）量子井戸構造によって構成され、バンド内遷移過程による光電変換のために用いられる。ｎ－ＧａＮ層１２は、バンド内遷移過程によって励起された電子を輸送するために用いられる。ｐ－ＧａＮ層１４は、バンド内遷移過程によって励起された正孔を輸送するために用いられる。従って、ｎ－ＧａＮ層１２およびｐ－ＧａＮ層１４の抵抗率および層厚はキャリア輸送を効率よく行うために、それぞれが好適に調整される。偏向部１５は、入射する赤外線の伝搬方向を偏向させ、この結果、入射赤外線の偏光を制御する。 The photosensitizing layer 13 has an indium nitride (InN) quantum well structure described below, and is used for photoelectric conversion by an in-band transition process. The n-GaN layer 12 is used to transport electrons excited by the intraband transition process. The p-GaN layer 14 is used to transport holes excited by the intraband transition process. Accordingly, the resistivity and the layer thickness of the n-GaN layer 12 and the p-GaN layer 14 are each suitably adjusted in order to efficiently transport carriers. The deflecting unit 15 deflects the propagation direction of incident infrared rays, and as a result, controls the polarization of incident infrared rays.
　次に、本願発明の第１の重要なポイントであるＩｎＮの物性について説明する。
　一般にＩｎＮは、ＧａＮ上に周知の半導体製造技術などで形成される。例えば、ｃ面成長する場合では、ＩｎＮとＧａＮでは約１１％の格子不整合度を有しているため、結晶成長中に高密度の格子欠陥が導入されてしまう。この格子欠陥は、光電変換効率を著しく劣化させる。ＩｎＮが格子欠陥を導入せずに弾性変形を保持し、ＧａＮに対してコヒーレント成長可能な膜厚の上限、すなわち臨界膜厚、が２分子層（２ＭＬ）であることを発明者らは見出した。 Next, the physical properties of InN, which is the first important point of the present invention, will be described.
In general, InN is formed on GaN by a known semiconductor manufacturing technique or the like. For example, when c-plane growth is performed, InN and GaN have a lattice mismatch of about 11%, so that high-density lattice defects are introduced during crystal growth. This lattice defect significantly deteriorates the photoelectric conversion efficiency. The inventors have found that the upper limit of the film thickness that allows InN to retain elastic deformation without introducing lattice defects and coherently grow with respect to GaN, that is, the critical film thickness, is a bimolecular layer (2ML). .
　さらに、この２分子層以下の超薄膜ＩｎＮでは、ＧａＮとの非混和性によって極めて構造完全性に優れた結晶成長が実現される。この結果、自己秩序的かつ自己停止的な形成プロセスが可能となり、原子層オーダで急峻なＩｎＮ／ＧａＮ界面が形成される。
　図２は、本実施形態に係る光増感層１３を示すブロック図である。図２に示されるように、前記超薄膜ＩｎＮによる量子井戸層と、ＧａＮ層による障壁層とで構成される量子井戸構造が、本実施形態に係る光増感層１３に対応する。 Furthermore, in this ultra-thin film InN having a bimolecular layer or less, crystal growth with extremely excellent structural integrity is realized by immiscibility with GaN. As a result, a self-ordered and self-stop forming process is possible, and a steep InN / GaN interface is formed on the atomic layer order.
FIG. 2 is a block diagram showing the photosensitizing layer 13 according to this embodiment. As shown in FIG. 2, the quantum well structure composed of the quantum well layer made of the ultrathin film InN and the barrier layer made of the GaN layer corresponds to the photosensitizing layer 13 according to the present embodiment.
　また、ＩｎＮの成長温度は、例えば分子線エピタキシー（ＭＢＥ）法では約６００℃以下に限られていたが、前記超薄膜ＩｎＮでは、６００℃以上の成長が可能となることも発明者らは見出した。この高温成長によって、超薄膜ＩｎＮの結晶性は飛躍的に向上する。この結果、光増感層１３は、高い光電変換効率（内部量子効率）を示す。このように、通常のバルクＩｎＮとは異なり、超薄膜ＩｎＮは特有の物性を示す。 In addition, although the growth temperature of InN was limited to about 600 ° C. or less in the molecular beam epitaxy (MBE) method, for example, the inventors found that the ultra-thin film InN can grow at 600 ° C. or more. It was. By this high temperature growth, the crystallinity of the ultra-thin film InN is dramatically improved. As a result, the photosensitizing layer 13 exhibits high photoelectric conversion efficiency (internal quantum efficiency). Thus, unlike ordinary bulk InN, ultrathin film InN exhibits specific physical properties.
　さらに、超薄膜ＩｎＮの成長温度とその層厚について、以下に説明する。
成長温度が６００℃から６５０℃の範囲では、２分子層ＩｎＮが自己秩序的かつ自己停止的に形成される。成長温度を約６５０℃とすると、１分子層ＩｎＮが自己秩序的かつ自己停止的に形成され、さらに温度を上げ、約６５０℃から約７２０℃の範囲では１分子層以下の分数層ＩｎＮが形成される。図３は、分数層ＩｎＮで構成される光増感層１３を示すブロック図である。図３に示されるように、分数層ＩｎＮとは、表面被覆率が１以下であることを意味し、例えば、０．５分子層とは、１分層厚かつ表面被覆率が５０％であるアイランド構造、すなわち、量子ディスク構造であることに対応する。 Further, the growth temperature and the layer thickness of the ultrathin film InN will be described below.
When the growth temperature is in the range of 600 ° C. to 650 ° C., the bimolecular layer InN is formed in a self-ordered and self-stopping manner. When the growth temperature is about 650 ° C., a monomolecular layer InN is formed in a self-ordered and self-stopping manner, and the temperature is further increased to form a fractional layer InN of one molecular layer or less in the range of about 650 ° C. to about 720 ° C. Is done. FIG. 3 is a block diagram showing the photosensitizing layer 13 composed of the fractional layer InN. As shown in FIG. 3, the fractional layer InN means that the surface coverage is 1 or less. For example, the 0.5 molecular layer is a one-layer thickness and the surface coverage is 50%. This corresponds to an island structure, that is, a quantum disk structure.
　超薄膜ＩｎＮの成長は、下地ＧａＮの表面モフォロジーに影響を受ける。ＧａＮの成長表面は、実際には原子層ステップの集合体によるうねり構造を示す。図４は、ＧａＮの表面うねり構造上に形成された超薄膜ＩｎＮによって構成される光増感層１３を示すブロック図である。図４に示されるように、ＧａＮの表面うねり構造上に超薄膜ＩｎＮを形成すると、この表面うねり構造を反映して、超薄膜ＩｎＮも同様の表面うねり構造を示す。この場合も、超薄膜ＩｎＮは、各原子層ステップのテラスごとに、高い構造完全性を有し、かつ自己秩序的かつ自己停止的な形成プロセスによって形成される。 The growth of ultra-thin InN is affected by the surface morphology of the underlying GaN. The growth surface of GaN actually shows a wavy structure due to an assembly of atomic layer steps. FIG. 4 is a block diagram showing the photosensitizing layer 13 composed of an ultrathin film InN formed on the surface wavy structure of GaN. As shown in FIG. 4, when an ultra-thin film InN is formed on the surface undulation structure of GaN, the ultra-thin film InN also shows a similar surface undulation structure, reflecting this surface undulation structure. Also in this case, the ultra-thin film InN is formed by a self-ordered and self-stop forming process having high structural integrity for each terrace of each atomic layer step.
　さらに、光増感層１３は、単層のみならず多層の超薄膜ＩｎＮによる多重量子井戸構造となる構成でもよい。この構成によれば、ＩｎＮ超薄膜による量子井戸の層数が増加するに従って、吸収する光量は増加するので、光電変換効率をより増強することができる。 Furthermore, the photosensitizing layer 13 may have a multi-quantum well structure made of not only a single layer but also a multilayer ultra-thin film InN. According to this configuration, the amount of light to be absorbed increases as the number of quantum well layers of the InN ultrathin film increases, so that the photoelectric conversion efficiency can be further enhanced.
　図５は、ＧａＮとＩｎＮのバンドラインナップを示した概念図である。図５では、図２と同様に、超薄膜ＩｎＮによる量子井戸層が、ＧａＮ障壁層によって挟まれており、ＣＢＭとＶＢＭは、伝導帯底部と価電子帯頂部をそれぞれ示し、図中左から右に向かってエネルギーが高くなる配置となっている。
　ＩｎＮとＧａＮのバンドギャップエネルギーはそれぞれ約０．６５ｅＶと３．４ｅＶであり、伝導帯バンドオフセットが約２ｅＶ、価電子帯バンドオフセットが約０．７５ｅＶである。これら大きなポテンシャル障壁は、ＩｎＮ層内のキャリアをほぼ完全に閉じ込めるため、このままでは室温での熱励起過程とあわせても、赤外線吸収によるバンド内遷移過程によってＩｎＮ層からキャリアをＧａＮ層へ、電流として取り出すことができない。すなわち、赤外線を検出することはできない。 FIG. 5 is a conceptual diagram showing a band lineup of GaN and InN. In FIG. 5, similarly to FIG. 2, a quantum well layer made of ultra-thin InN is sandwiched between GaN barrier layers, and CBM and VBM indicate the bottom of the conduction band and the top of the valence band, respectively. It becomes the arrangement where the energy becomes higher toward.
The band gap energies of InN and GaN are about 0.65 eV and 3.4 eV, respectively, the conduction band offset is about 2 eV, and the valence band offset is about 0.75 eV. These large potential barriers almost completely confine the carriers in the InN layer. Therefore, even if this is combined with the thermal excitation process at room temperature, the carriers are transferred from the InN layer to the GaN layer as a current by the in-band transition process by infrared absorption. It cannot be taken out. That is, infrared rays cannot be detected.
　一方、ＩｎＮ層の層厚をナノメートルオーダまで薄くしていくと、電子および正孔の量子準位Ｅｃ、Ｅｖが、図中点線のエネルギー位置に形成される。この量子サイズ効果により、超薄膜ＩｎＮの実効バンドギャップエネルギー（ＥｃとＥｖとの差）は０．６５ｅＶからシフトする。例えば、２分子層ＩｎＮでは、前記実効バンドギャップエネルギーは、常にＧａＮのバンドギャップエネルギーより５００ｍｅＶ低くなり、１分子層ＩｎＮでは前記実効バンドギャップエネルギーは、常にＧａＮのバンドギャップエネルギーより２００ｍｅＶ低くなることを発明者らは見出した。 On the other hand, when the layer thickness of the InN layer is reduced to the nanometer order, quantum levels Ec and Ev of electrons and holes are formed at the energy positions indicated by dotted lines in the figure. Due to this quantum size effect, the effective band gap energy (difference between Ec and Ev) of the ultrathin film InN is shifted from 0.65 eV. For example, in the bimolecular layer InN, the effective band gap energy is always 500 meV lower than the band gap energy of GaN, and in the monomolecular layer InN, the effective band gap energy is always 200 meV lower than the band gap energy of GaN. The inventors have found.
　超薄膜ＩｎＮが自己秩序的かつ自己停止的に得られるため、前記実効バンドギャップエネルギーとＧａＮのバンドギャップエネルギー差も、それぞれ２分子層では約５００ｍｅＶ、１分子層では約２００ｍｅＶと自動的に制御される。このように、超薄膜ＩｎＮの構造完全性によって、前記実効バンドギャップエネルギーは、容易かつ精密に決定される。これらの値は、上述した通常のＩｎＮとＧａＮの場合と比べて大幅に低減されている。つまり、光増感層１３を２分子層以下の構成とすることで、赤外線吸収によるバンド内遷移過程でも、十分に光増感層１３からｎ－ＧａＮ層１２およびｐ－ＧａＮ層１４へ、キャリアが移動自在となり、電流として取り出せる。すなわち、赤外線を検出することが可能となる。 Since ultra-thin InN is obtained in a self-ordered and self-stopping manner, the difference between the effective band gap energy and the band gap energy of GaN is automatically controlled to about 500 meV for the bimolecular layer and about 200 meV for the single molecular layer. The Thus, the effective band gap energy is easily and precisely determined by the structural integrity of the ultra-thin film InN. These values are greatly reduced as compared with the above-described normal InN and GaN. That is, by configuring the photosensitizing layer 13 to have two or less molecular layers, carriers can be sufficiently transferred from the photosensitizing layer 13 to the n-GaN layer 12 and the p-GaN layer 14 even in the in-band transition process by infrared absorption. Becomes movable and can be taken out as an electric current. That is, it becomes possible to detect infrared rays.
　本願発明の第２の重要なポイントである偏向部１５の作用および効果について説明する。
　光増感層１３において、バンド内遷移過程を許容にするためには、入射する赤外光の偏光が、光増感層１３の積層方向の成分を含んでいることが要求される。言い換えれば、図２におけるＩｎＮ量子井戸面に対して、垂直な偏光成分を含んでいることが要求される。すなわち、光電変換装置１０に垂直上方から入射する赤外線に対して、この偏光選択則を満足させるために、偏向部１５は、入射する赤外線の伝搬方向を偏向させ、入射赤外線がｐ偏光成分を有するよう好適に制御する。これによって、図１０で示される斜め入射の配置と同様に、光増感層１３に対するｐ偏光成分が発現することになるので、前記偏光選択則が満足されることを発明者らは見出した。 The operation and effect of the deflecting portion 15 which is the second important point of the present invention will be described.
In order to allow the in-band transition process in the photosensitizing layer 13, it is required that the incident infrared light polarization includes a component in the stacking direction of the photosensitizing layer 13. In other words, it is required to include a polarization component perpendicular to the InN quantum well surface in FIG. That is, in order to satisfy this polarization selection rule for infrared rays incident on the photoelectric conversion device 10 from vertically above, the deflecting unit 15 deflects the propagation direction of the incident infrared rays, and the incident infrared rays have a p-polarized component. It controls suitably. As a result, the inventors have found that the polarization selection rule is satisfied because the p-polarized component with respect to the photosensitizing layer 13 is expressed in the same manner as the oblique incidence arrangement shown in FIG.
　入射赤外線の伝搬方向を偏向させるために、偏向部１５は、不均質な屈折率分布によって構成となる。例えば、この不均質な屈折率とは、平坦な膜構造の場合、屈折率が内部で変化していることに対応する一方、屈折率が均一な媒質の場合、平坦でない膜構造に対応する。 In order to deflect the propagation direction of incident infrared rays, the deflecting unit 15 is configured by a non-uniform refractive index distribution. For example, this inhomogeneous refractive index corresponds to the fact that the refractive index varies internally in the case of a flat film structure, while it corresponds to a non-flat film structure in the case of a medium having a uniform refractive index.
　以下では、本願発明に係る光電変換装置を構成する偏向部の構成について、図６～図８を参照して説明する。ただし、これ以外については、図１に示される構成と同様であるので、その説明は割愛する。 Hereinafter, the configuration of the deflecting unit constituting the photoelectric conversion device according to the present invention will be described with reference to FIGS. However, since the configuration other than this is the same as that shown in FIG. 1, the description thereof is omitted.
［実施例１］
　図６は、本願発明の第１の実施例である光電変換装置２０の構成を示すブロック図である。図６において、光電変換装置２０は、ｎ型窒化ガリウム（ｎ－ＧａＮ）層２２と、ｎ－ＧａＮ層２２上に形成される光増感層２３と、光増感層２３上に形成されるｐ型窒化ガリウム（ｐ－ＧａＮ）層２４と、ｐ－ＧａＮ層２４上に形成される偏向部２５と、によって構成される。偏向部２５は、赤外線の入射面に凹凸構造を有する構成となっている。 [Example 1]
FIG. 6 is a block diagram showing the configuration of the photoelectric conversion apparatus 20 according to the first embodiment of the present invention. In FIG. 6, the photoelectric conversion device 20 is formed on an n-type gallium nitride (n-GaN) layer 22, a photosensitizing layer 23 formed on the n-GaN layer 22, and the photosensitizing layer 23. The p-type gallium nitride (p-GaN) layer 24 and the deflection unit 25 formed on the p-GaN layer 24 are configured. The deflecting unit 25 has a concavo-convex structure on the infrared incident surface.
　赤外線が偏向部２５に垂直入射する場合、偏向部２５の入射面に存在する凹凸構造は、反射や屈折によって、赤外線の伝搬方向を偏向させる。このため、この凹凸の段差や間隔などの寸法は、入射される赤外線の波長と同程度、もしくはそれよりも大きくなる。この結果、実効的な入射方向は、垂直方向から外れ、斜め入射と同様と見なせる。言い換えれば、光増感層２３に対するｐ偏光成分が発現することになるので、バンド内遷移過程を許容するための偏光選択則が満足される。この結果、赤外線を検出することが可能となる。
　さらに、赤外線が偏向部２５に斜め入射する場合、偏向部２５の入射面に存在する凹凸構造によって、平坦な場合と比べて、表面反射率が抑制されているので、実効的な光取り込み効率が向上する。 When infrared light is incident on the deflecting unit 25 perpendicularly, the concavo-convex structure present on the incident surface of the deflecting unit 25 deflects the propagation direction of the infrared by reflection or refraction. For this reason, the dimensions of the unevenness, step and interval of the unevenness are approximately the same as or larger than the wavelength of incident infrared rays. As a result, the effective incident direction deviates from the vertical direction and can be regarded as the same as the oblique incident. In other words, since the p-polarized component for the photosensitizing layer 23 is expressed, the polarization selection rule for allowing the in-band transition process is satisfied. As a result, infrared rays can be detected.
Further, when infrared rays are incident obliquely on the deflecting unit 25, the surface reflectance is suppressed by the uneven structure present on the incident surface of the deflecting unit 25 compared to a flat case, so that effective light capturing efficiency is improved. improves.
　偏向部２５の凹凸構造は、周知の半導体製造技術などで形成される窒化物半導体のエッチング加工、または選択成長によるファセットによって形成される。またこれ以外にも、周知の製膜技術などで形成される材料のエッチング加工によって形成される。この誘電体とは、例えば、酸化亜鉛（ＺｎＯ）、酸化インジウムスズ（ＩＴＯ）、二酸化珪素（ＳｉＯ２）、二酸化チタン（ＴｉＯ２）、または二酸化ジルコニウム（ＺｒＯ２）などによって構成される。 The concavo-convex structure of the deflecting portion 25 is formed by faceting by etching or selective growth of a nitride semiconductor formed by a known semiconductor manufacturing technique or the like. In addition to this, it is formed by etching a material formed by a known film forming technique or the like. This dielectric is made of, for example, zinc oxide (ZnO), indium tin oxide (ITO), silicon dioxide (SiO 2 ), titanium dioxide (TiO 2 ), or zirconium dioxide (ZrO 2 ).
［実施例２］
　図７は、本願発明の第２の実施例である光電変換装置３０の構成を示すブロック図である。図７において、光電変換装置３０は、ｎ型窒化ガリウム（ｎ－ＧａＮ）層３２と、ｎ－ＧａＮ層３２上に形成される光増感層３３と、光増感層３３上に形成されるｐ型窒化ガリウム（ｐ－ＧａＮ）層３４と、ｐ－ＧａＮ層３４上に形成される偏向部３５と、によって構成される。偏向部３５は、微粒子状の構造によって構成される。 [Example 2]
FIG. 7 is a block diagram showing a configuration of a photoelectric conversion apparatus 30 according to the second embodiment of the present invention. In FIG. 7, the photoelectric conversion device 30 is formed on an n-type gallium nitride (n-GaN) layer 32, a photosensitizing layer 33 formed on the n-GaN layer 32, and the photosensitizing layer 33. The p-type gallium nitride (p-GaN) layer 34 and the deflecting portion 35 formed on the p-GaN layer 34 are configured. The deflection unit 35 is configured by a fine particle structure.
　赤外線が偏向部３５に垂直入射する場合、偏向部３５を構成する微粒子構造は、反射や屈折によって、赤外線の伝搬方向を偏向させる。このため、この微粒子の粒径は、入射される赤外線の波長と同程度、もしくはそれよりも大きくなる。この結果、実効的な入射方向は、垂直方向から外れ、斜め入射と同様と見なせる。言い換えれば、光増感層３３に対するｐ偏光成分が発現することになるので、バンド内遷移過程を許容するための偏光選択則が満足される。この結果、赤外線を検出することが可能となる。
　さらに、赤外線が偏向部３５に斜め入射する場合、偏向部３５の入射面に存在する表面構造によって、平坦な場合と比べて、表面反射率が抑制されているので、実効的な光取り込み効率が向上する。 When infrared rays are perpendicularly incident on the deflection unit 35, the fine particle structure constituting the deflection unit 35 deflects the propagation direction of the infrared rays by reflection or refraction. For this reason, the particle diameter of the fine particles is approximately the same as or larger than the wavelength of the incident infrared rays. As a result, the effective incident direction deviates from the vertical direction and can be regarded as the same as the oblique incident. In other words, since the p-polarized light component for the photosensitizing layer 33 appears, the polarization selection rule for allowing the in-band transition process is satisfied. As a result, infrared rays can be detected.
Further, when infrared rays are incident obliquely on the deflecting portion 35, the surface reflectance is suppressed by the surface structure existing on the incident surface of the deflecting portion 35 as compared with a flat case, so that effective light capturing efficiency is improved. improves.
　偏向部３５の微粒子構造は、周知の半導体製造技術などで形成される窒化物半導体のエッチング加工、または選択成長によって形成される。またこれ以外にも、周知の製造技術などで形成される微小球をｐ－ＧａＮ層３４上へのコーティング加工によって形成される。この微小球は、例えば、酸化亜鉛（ＺｎＯ）、酸化インジウムスズ（ＩＴＯ）、二酸化珪素（ＳｉＯ２）、二酸化チタン（ＴｉＯ２）、または二酸化ジルコニウム（ＺｒＯ２）などによって構成される。 The fine particle structure of the deflection unit 35 is formed by etching or selective growth of a nitride semiconductor formed by a known semiconductor manufacturing technique or the like. In addition to this, microspheres formed by a known manufacturing technique or the like are formed by coating the p-GaN layer 34. The microspheres are made of, for example, zinc oxide (ZnO), indium tin oxide (ITO), silicon dioxide (SiO 2 ), titanium dioxide (TiO 2 ), or zirconium dioxide (ZrO 2 ).
［実施例３］
　図８は、本願発明の第３の実施例である光電変換装置４０の構成を示すブロック図である。図８において、光電変換装置４０は、ｎ型窒化ガリウム（ｎ－ＧａＮ）層４２と、ｎ－ＧａＮ層４２上に形成される光増感層４３と、光増感層４３上に形成されるｐ型窒化ガリウム（ｐ－ＧａＮ）層４４と、ｎ－ＧａＮ層４２とＩｎＮ光増感層４３とｐ－ＧａＮ層４４とを囲むように形成される偏向部４５と、によって構成される。偏向部４５は、例えば、表面に凹凸構造を有する、もしく微粒子状の構造によって構成されてもよい。 [Example 3]
FIG. 8 is a block diagram showing a configuration of a photoelectric conversion apparatus 40 according to the third embodiment of the present invention. In FIG. 8, a photoelectric conversion device 40 is formed on an n-type gallium nitride (n-GaN) layer 42, a photosensitizing layer 43 formed on the n-GaN layer 42, and the photosensitizing layer 43. A p-type gallium nitride (p-GaN) layer 44, an n-GaN layer 42, an InN photosensitizing layer 43, and a deflection unit 45 formed so as to surround the p-GaN layer 44 are configured. For example, the deflecting unit 45 may have a concavo-convex structure on the surface or a fine particle structure.
　赤外線が偏向部４５に入射する場合、偏向部４５は屈折によって、あらゆる方位から入射される赤外線の伝搬方向を偏向させる。この結果、光増感層４３に対するｐ偏光成分が発現することになるので、バンド内遷移過程を許容するための偏光選択則が満足される。この結果、赤外線を検出することが可能となる。
　さらに、偏向部４５には、あらゆる方位からの赤外線が入射可能であるので、実効的な受光面積が増大し、光取り込み効率が向上する。 When infrared rays are incident on the deflecting unit 45, the deflecting unit 45 deflects the propagation direction of the infrared rays incident from all directions by refraction. As a result, a p-polarized component for the photosensitizing layer 43 appears, so that the polarization selection rule for allowing the in-band transition process is satisfied. As a result, infrared rays can be detected.
Furthermore, since the infrared rays from all directions can be incident on the deflecting unit 45, the effective light receiving area is increased and the light capturing efficiency is improved.
　偏向部４５は、周知の半導体製造技術などで形成される窒化物半導体の製膜工程、またはエッチング加工によって形成される。またこれ以外にも、周知の製造技術などで形成される材料によって形成される。この誘電体とは、例えば、酸化亜鉛（ＺｎＯ）、酸化インジウムスズ（ＩＴＯ）、二酸化珪素（ＳｉＯ２）、二酸化チタン（ＴｉＯ２）、または二酸化ジルコニウム（ＺｒＯ２）などによって構成される。 The deflection unit 45 is formed by a nitride semiconductor film forming process formed by a known semiconductor manufacturing technique or the like, or an etching process. In addition to this, it is formed of a material formed by a known manufacturing technique or the like. This dielectric is made of, for example, zinc oxide (ZnO), indium tin oxide (ITO), silicon dioxide (SiO 2 ), titanium dioxide (TiO 2 ), or zirconium dioxide (ZrO 2 ).
［第２実施形態］
　第１実施形態では、本願発明に係る光電変換装置として、バンド内遷移過程を利用した赤外線検出について述べた。本実施形態では、バンド内遷移過程を外部光によって制御する、赤外線のスイッチング、すなわち、光－光変調、について述べる。
　以下の説明では、本願発明に係る光電変換装置の構成は、第１実施形態と同様であるので、赤外線の光－光変調の動作原理について図１および図９を参照して述べる。 [Second Embodiment]
In the first embodiment, infrared detection using an in-band transition process has been described as the photoelectric conversion device according to the present invention. In this embodiment, infrared switching, that is, light-light modulation, in which the intraband transition process is controlled by external light will be described.
In the following description, since the configuration of the photoelectric conversion device according to the present invention is the same as that of the first embodiment, the operation principle of infrared light-light modulation will be described with reference to FIGS.
　図９は、ＧａＮとＩｎＮのバンドラインナップを示した概念図である。図９では、図２と同様に、超薄膜ＩｎＮによる量子井戸層が、ＧａＮ障壁層によって挟まれており、ＣＢＭとＶＢＭは、伝導帯底部と価電子帯頂部をそれぞれ示し、図中左から右に向かってエネルギーが高くなる配置となっている。量子井戸における電子および正孔の量子準位Ｅｃ、Ｅｖが、図中点線のエネルギー位置に形成され、超薄膜ＩｎＮの実効バンドギャップエネルギーは、ＥｃとＥｖとの差に対応する。 FIG. 9 is a conceptual diagram showing a band lineup of GaN and InN. In FIG. 9, similarly to FIG. 2, a quantum well layer made of ultra-thin InN is sandwiched between GaN barrier layers, and CBM and VBM indicate the bottom of the conduction band and the top of the valence band, respectively. It becomes the arrangement where the energy becomes higher toward. The quantum levels Ec and Ev of electrons and holes in the quantum well are formed at the energy positions indicated by dotted lines in the figure, and the effective band gap energy of the ultrathin film InN corresponds to the difference between Ec and Ev.
　前述した様に、超薄膜ＩｎＮの実効バンドギャップエネルギーは、通常のＩｎＮのバンドギャップエネルギーである約０．６５ｅＶとは大きく異なり、２分子層ＩｎＮでは、前記実効バンドギャップエネルギーは、常にＧａＮのバンドギャップエネルギーより５００ｍｅＶ低くなり、１分子層ＩｎＮでは前記実効バンドギャップエネルギーは、常にＧａＮのバンドギャップエネルギーより２００ｍｅＶ低くなる。そのため、前記実効バンドギャップエネルギーは、２．９ｅＶ以上に対応する。 As described above, the effective band gap energy of the ultra-thin film InN is greatly different from about 0.65 eV which is the band gap energy of normal InN. In the bimolecular layer InN, the effective band gap energy is always the band of GaN. 500 meV lower than the gap energy, and in the single molecular layer InN, the effective band gap energy is always 200 meV lower than the band gap energy of GaN. Therefore, the effective band gap energy corresponds to 2.9 eV or more.
　このため、光電変換装置１０に、２．９ｅＶ以上のエネルギーの光が入射すると、光増感層１３におけるＩｎＮ量子井戸層には、光励起キャリアが生成される。さらに、前述したように、赤外線が偏向部１５を介して光電変換装置１０に入射すると、ＩｎＮ量子井戸層に存在する前記光励起キャリアは、バンド内遷移過程を引き起こす。すなわち、光電変換装置１０に、２．９ｅＶより大きなエネルギーの光が入射したときのみ、赤外線の吸収が起こることになる。言い換えると、光電変換装置１０は、２．９ｅＶ以上のエネルギーの外部光によって、赤外光のスイッチング、すなわち、光－光変調を行うことが可能となる。 Therefore, when light having an energy of 2.9 eV or more enters the photoelectric conversion device 10, photoexcited carriers are generated in the InN quantum well layer in the photosensitizing layer 13. Furthermore, as described above, when infrared rays enter the photoelectric conversion device 10 via the deflecting unit 15, the photoexcited carriers present in the InN quantum well layer cause an in-band transition process. That is, infrared absorption occurs only when light having an energy greater than 2.9 eV is incident on the photoelectric conversion device 10. In other words, the photoelectric conversion device 10 can perform infrared light switching, that is, light-light modulation, with external light having an energy of 2.9 eV or more.
　なお、上述した実施形態では、ｐｎ接合および量子井戸の障壁層がＧａＮによって構成される例について述べたが、これだけに限定されず、例えば、窒化インジウムガリウムアルミニウム（以下、ＩｎｘＧａｙＡｌ１－ｘ－ｙＮ、ｘおよびｙの範囲は０≦ｘ，ｙ≦１）による構成も可能である。 In the above-described embodiment, an example in which the barrier layer of the pn junction and the quantum well is made of GaN has been described. However, the present invention is not limited to this. For example, indium gallium aluminum nitride (hereinafter, In x Ga y Al 1-1) is used. The range of xy N, x, and y can be configured by 0 ≦ x, y ≦ 1).
　また、本願発明は、上記実施形態によって限定されるものではなく、発明の意図から逸脱しない範囲での、変形、置換、省略がなされてもよいものとする。 The present invention is not limited to the above-described embodiment, and modifications, substitutions, and omissions may be made without departing from the spirit of the invention.
　本発明に係る光電変換装置は、中赤外光に対応する検出器および変調器、もしくは太陽電池における光増感機能に好適な光電変換装置に利用が可能である。 The photoelectric conversion device according to the present invention can be used for a detector and a modulator corresponding to mid-infrared light, or a photoelectric conversion device suitable for a photosensitization function in a solar cell.
　１０，２０，３０，４０，１００…光電変換装置　１２，２２，３２，４２…ｎ型ＧａＮ層　１３，２３，３３，４３…光増感層　１４，２４，３４，４４…ｐ型ＧａＮ層　１５，２５，３５，４５…偏向部　１０２，１０４…障壁層　１０３…量子井戸層  10, 20, 30, 40, 100 ... photoelectric conversion device 12, 22, 32, 42 ... n- type GaN layer 13, 23, 33, 43 ... photosensitized layer 14, 24, 34, 44 ... p- type GaN layer 15 , 25, 35, 45 ... deflection unit 102, 104 ... barrier layer 103 ... quantum well layer

Claims (11)

  1. 　第１伝導型からなる第１伝導層と、
    　前記第１伝導層上に形成される光増感層と、
    　前記光増感層上に形成され、第２伝導型からなる第２伝導層と、
    　前記第２伝導層上に形成される偏向部と、を備える光電変換装置であって、
    　前記光増感層は、バンド内遷移過程による光電変換を行う光電変換装置。     A first conductive layer of the first conductivity type;
    A photosensitizing layer formed on the first conductive layer;
    A second conductive layer formed on the photosensitizing layer and having a second conductivity type;
    A deflection unit formed on the second conductive layer, comprising:
    The photosensitizing layer is a photoelectric conversion device that performs photoelectric conversion by an in-band transition process.
  2. 　前記第１伝導層は第１バンドギャップエネルギーを有し、
    　前記第２伝導層は第２バンドギャップエネルギーを有し、
    　前記光増感層は第３バンドギャップエネルギーを有し、
    　前記第３バンドギャップエネルギーは前記第１および前記第２バンドギャップエネルギーよりも小さい請求項１に記載の光電変換装置。     The first conductive layer has a first band gap energy;
    The second conductive layer has a second band gap energy;
    The photosensitizing layer has a third band gap energy;
    The photoelectric conversion device according to claim 1, wherein the third band gap energy is smaller than the first and second band gap energies.
  3. 　前記偏向部は、表面に凹凸形状を有する請求項１に記載の光電変換装置。 The photoelectric conversion device according to claim 1, wherein the deflection unit has an uneven shape on a surface thereof.
  4. 　前記偏向部は、微粒子によって構成される請求項１に記載の光電変換装置。 The photoelectric conversion device according to claim 1, wherein the deflection unit is configured by fine particles.
  5. 　前記偏向部は、前記第１伝導層と、前記光増感層と、前記第２伝導層と、を囲むように構成される請求項１に記載の光電変換装置。 The photoelectric conversion device according to claim 1, wherein the deflecting unit is configured to surround the first conductive layer, the photosensitizing layer, and the second conductive layer.
  6. 　前記光増感層は、前記第３バンドギャップエネルギーよりも高エネルギーの光吸収によって生成されたキャリアに対して、前記バンド内遷移過程による前記光電変換を行う
    請求項２に記載の光電変換装置。     3. The photoelectric conversion device according to claim 2, wherein the photosensitizing layer performs the photoelectric conversion by the intra-band transition process on carriers generated by light absorption of energy higher than the third band gap energy.
  7. 　第１伝導型からなる第１ＩｎｘＧａｙＡｌ１－ｘ－ｙＮ層と、
    　前記第１ＩｎｘＧａｙＡｌ１－ｘ－ｙＮ層上に形成される光増感層と、
    　前記光増感層上に形成され、第２伝導型からなる第２ＩｎｘＧａｙＡｌ１－ｘ－ｙＮ層と、
    前記第２ＩｎｘＧａｙＡｌ１－ｘ－ｙＮ層上に形成される偏向部と、を備える光電変換装置であって、
    　前記ｘおよびｙの範囲は０≦ｘ，ｙ≦１であり、
    　前記光増感層は、層厚が２分子層以下のＩｎＮを含み、
    　前記光増感層におけるキャリアが、前記第１ＩｎｘＧａｙＡｌ１－ｘ－ｙＮ層および前記第２ＩｎｘＧａｙＡｌ１－ｘ－ｙＮ層の少なくともいずれかに、バンド内遷移過程によって移動自在である光電変換装置。     A first 1In x Ga y Al 1-x -y N layer made of a first conduction type,
    A photosensitizing layer formed on the first In x Ga y Al 1-xy N layer;
    A second In x Ga y Al 1-xy N layer formed on the photosensitizing layer and having a second conductivity type;
    A deflection unit formed on the second In x Ga y Al 1-xy N layer,
    The ranges of x and y are 0 ≦ x, y ≦ 1,
    The photosensitizing layer contains InN having a layer thickness of 2 molecular layers or less,
    Moving carrier in the sensitized layer is, the to the 1In x Ga y Al 1-x -y N layer and said second 2In x Ga y Al 1-x -y N least one of layers, the intraband transition process A flexible photoelectric conversion device.
  8. 　前記偏向部は、表面に凹凸形状を有する請求項７に記載の光電変換装置。 The photoelectric conversion device according to claim 7, wherein the deflection unit has an uneven shape on a surface.
  9. 　前記偏向部は、微粒子によって構成される請求項７に記載の光電変換装置。 The photoelectric conversion device according to claim 7, wherein the deflection unit is configured by fine particles.
  10. 　前記偏向部は、前記第１ＩｎｘＧａｙＡｌ１－ｘ－ｙＮ層と、前記光増感層と、前記第２ＩｎｘＧａｙＡｌ１－ｘ－ｙＮ層と、を囲むように構成される請求項７に記載の光電変換装置。 The deflection unit, the a first 1In x Ga y Al 1-x -y N layer, said photosensitizing layer is configured to surround, said first 2In x Ga y Al 1-x -y N layer The photoelectric conversion device according to claim 7.
  11. 　前記光増感層は、前記光増感層の実効バンドギャップエネルギーよりも高エネルギーの光吸収によって生成されたキャリアに対して、前記バンド内遷移過程による前記光電変換を行う請求項７に記載の光電変換装置。 The said photosensitizing layer performs the said photoelectric conversion by the said in-band transition process with respect to the carrier produced | generated by the light absorption of energy higher than the effective band gap energy of the said photosensitizing layer. Photoelectric conversion device.
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