WO2010104111A1 - 透明導電膜と透明導電膜積層体及びその製造方法、並びにシリコン系薄膜太陽電池 - Google Patents
透明導電膜と透明導電膜積層体及びその製造方法、並びにシリコン系薄膜太陽電池 Download PDFInfo
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- WO2010104111A1 WO2010104111A1 PCT/JP2010/054004 JP2010054004W WO2010104111A1 WO 2010104111 A1 WO2010104111 A1 WO 2010104111A1 JP 2010054004 W JP2010054004 W JP 2010054004W WO 2010104111 A1 WO2010104111 A1 WO 2010104111A1
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- Prior art keywords
- transparent conductive
- conductive film
- film
- indium oxide
- zinc oxide
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- 239000010408 film Substances 0.000 title claims abstract description 808
- 239000010409 thin film Substances 0.000 title claims abstract description 104
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 46
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 46
- 239000010703 silicon Substances 0.000 title claims abstract description 46
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 41
- 238000000034 method Methods 0.000 title abstract description 47
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims abstract description 378
- 239000011787 zinc oxide Substances 0.000 claims abstract description 188
- 229910052733 gallium Inorganic materials 0.000 claims abstract description 50
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 claims abstract description 49
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 49
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 45
- 230000003746 surface roughness Effects 0.000 claims abstract description 41
- 239000011701 zinc Substances 0.000 claims abstract description 34
- 229910052751 metal Inorganic materials 0.000 claims abstract description 24
- 229910003437 indium oxide Inorganic materials 0.000 claims description 132
- PJXISJQVUVHSOJ-UHFFFAOYSA-N indium(iii) oxide Chemical compound [O-2].[O-2].[O-2].[In+3].[In+3] PJXISJQVUVHSOJ-UHFFFAOYSA-N 0.000 claims description 132
- 239000000758 substrate Substances 0.000 claims description 87
- 238000006243 chemical reaction Methods 0.000 claims description 63
- 238000004544 sputter deposition Methods 0.000 claims description 49
- 239000013078 crystal Substances 0.000 claims description 31
- 239000004065 semiconductor Substances 0.000 claims description 17
- 239000000654 additive Substances 0.000 claims description 14
- 230000000996 additive effect Effects 0.000 claims description 14
- 229910052718 tin Inorganic materials 0.000 claims description 12
- 229910052719 titanium Inorganic materials 0.000 claims description 12
- 229910052750 molybdenum Inorganic materials 0.000 claims description 10
- 229910052721 tungsten Inorganic materials 0.000 claims description 10
- 230000000694 effects Effects 0.000 abstract description 37
- 239000001257 hydrogen Substances 0.000 abstract description 13
- 229910052739 hydrogen Inorganic materials 0.000 abstract description 13
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 abstract description 12
- 239000002184 metal Substances 0.000 abstract description 10
- 230000001747 exhibiting effect Effects 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 108
- 239000000203 mixture Substances 0.000 description 78
- 230000015572 biosynthetic process Effects 0.000 description 70
- 239000007789 gas Substances 0.000 description 48
- 238000011156 evaluation Methods 0.000 description 30
- 238000010438 heat treatment Methods 0.000 description 24
- 239000010936 titanium Substances 0.000 description 22
- 238000002441 X-ray diffraction Methods 0.000 description 14
- 238000002834 transmittance Methods 0.000 description 12
- 230000003247 decreasing effect Effects 0.000 description 11
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 10
- 238000000151 deposition Methods 0.000 description 9
- 230000008021 deposition Effects 0.000 description 9
- 239000002019 doping agent Substances 0.000 description 9
- 229910052760 oxygen Inorganic materials 0.000 description 9
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 8
- 229910001887 tin oxide Inorganic materials 0.000 description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 7
- 239000011521 glass Substances 0.000 description 7
- 239000001301 oxygen Substances 0.000 description 7
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 6
- 229910021417 amorphous silicon Inorganic materials 0.000 description 6
- 239000012528 membrane Substances 0.000 description 6
- 229910052725 zinc Inorganic materials 0.000 description 6
- 230000002159 abnormal effect Effects 0.000 description 5
- 229910052786 argon Inorganic materials 0.000 description 5
- 229910021419 crystalline silicon Inorganic materials 0.000 description 5
- 229910052738 indium Inorganic materials 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000005477 sputtering target Methods 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 238000000137 annealing Methods 0.000 description 4
- 230000031700 light absorption Effects 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 4
- 229910010271 silicon carbide Inorganic materials 0.000 description 4
- 238000004611 spectroscopical analysis Methods 0.000 description 4
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 3
- AJNVQOSZGJRYEI-UHFFFAOYSA-N digallium;oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Ga+3].[Ga+3] AJNVQOSZGJRYEI-UHFFFAOYSA-N 0.000 description 3
- 229910001195 gallium oxide Inorganic materials 0.000 description 3
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 3
- 229910052749 magnesium Inorganic materials 0.000 description 3
- 239000011777 magnesium Substances 0.000 description 3
- 229910044991 metal oxide Inorganic materials 0.000 description 3
- 150000004706 metal oxides Chemical class 0.000 description 3
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 3
- 238000002230 thermal chemical vapour deposition Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000003570 air Substances 0.000 description 2
- 239000012298 atmosphere Substances 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000005684 electric field Effects 0.000 description 2
- 229910052731 fluorine Inorganic materials 0.000 description 2
- 239000011737 fluorine Substances 0.000 description 2
- 229910052732 germanium Inorganic materials 0.000 description 2
- 239000004973 liquid crystal related substance Substances 0.000 description 2
- 238000001755 magnetron sputter deposition Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 229910021424 microcrystalline silicon Inorganic materials 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000011733 molybdenum Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 238000005268 plasma chemical vapour deposition Methods 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 229910052596 spinel Inorganic materials 0.000 description 2
- 239000011029 spinel Substances 0.000 description 2
- 238000002233 thin-film X-ray diffraction Methods 0.000 description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 2
- 239000010937 tungsten Substances 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910052684 Cerium Inorganic materials 0.000 description 1
- 229910013973 M18XHF22 Inorganic materials 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 229910006404 SnO 2 Inorganic materials 0.000 description 1
- FMRLDPWIRHBCCC-UHFFFAOYSA-L Zinc carbonate Chemical compound [Zn+2].[O-]C([O-])=O FMRLDPWIRHBCCC-UHFFFAOYSA-L 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052787 antimony Inorganic materials 0.000 description 1
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 1
- 239000012736 aqueous medium Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- ZMIGMASIKSOYAM-UHFFFAOYSA-N cerium Chemical compound [Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce] ZMIGMASIKSOYAM-UHFFFAOYSA-N 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 239000002178 crystalline material Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 230000005294 ferromagnetic effect Effects 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- AMGQUBHHOARCQH-UHFFFAOYSA-N indium;oxotin Chemical compound [In].[Sn]=O AMGQUBHHOARCQH-UHFFFAOYSA-N 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 230000005291 magnetic effect Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000013081 microcrystal Substances 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
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- 238000000984 pole figure measurement Methods 0.000 description 1
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- 238000011160 research Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 229910052702 rhenium Inorganic materials 0.000 description 1
- WUAPFZMCVAUBPE-UHFFFAOYSA-N rhenium atom Chemical compound [Re] WUAPFZMCVAUBPE-UHFFFAOYSA-N 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000012780 transparent material Substances 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Images
Classifications
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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
- H01L31/02—Details
- H01L31/0224—Electrodes
- H01L31/022466—Electrodes made of transparent conductive layers, e.g. TCO, ITO layers
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- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/453—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on zinc, tin, or bismuth oxides or solid solutions thereof with other oxides, e.g. zincates, stannates or bismuthates
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/0021—Reactive sputtering or evaporation
- C23C14/0036—Reactive sputtering
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
- C23C14/08—Oxides
- C23C14/086—Oxides of zinc, germanium, cadmium, indium, tin, thallium or bismuth
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/06—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances
- H01B1/08—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances oxides
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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
- H01L31/02—Details
- H01L31/0224—Electrodes
- H01L31/022466—Electrodes made of transparent conductive layers, e.g. TCO, ITO layers
- H01L31/022483—Electrodes made of transparent conductive layers, e.g. TCO, ITO layers composed of zinc oxide [ZnO]
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- H—ELECTRICITY
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- H01L31/02—Details
- H01L31/0236—Special surface textures
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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
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
- H01L31/1884—Manufacture of transparent electrodes, e.g. TCO, ITO
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- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
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- C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
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- C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/3286—Gallium oxides, gallates, indium oxides, indates, thallium oxides, thallates or oxide forming salts thereof, e.g. zinc gallate
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- 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
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- 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
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Definitions
- the present invention relates to a transparent conductive film, a transparent conductive film laminate, a method for manufacturing the same, and a silicon-based thin film solar cell. More specifically, the hydrogen-resistant reduction resistance useful for manufacturing a high-efficiency silicon-based thin film solar cell.
- the present invention relates to a transparent conductive film excellent in light confinement effect, a transparent conductive film laminate using the same, and a method for producing the same, and a silicon-based thin film solar cell using the transparent conductive film or transparent conductive film laminate as an electrode.
- Transparent conductive films with high conductivity and high transmittance in the visible light region are used for electrodes of solar cells, liquid crystal display elements, and other various light receiving elements, and in addition, heat ray reflection for automobile windows and buildings. It is also used as a transparent heating element for various types of antifogging, such as a film, an antistatic film, and a frozen showcase.
- tin oxide (SnO 2 ) -based, zinc oxide (ZnO) -based, and indium oxide (In 2 O 3 ) -based thin films are known.
- tin oxide those containing antimony as a dopant (ATO) and those containing fluorine as a dopant (FTO) are used.
- zinc oxide system those containing aluminum as a dopant (AZO) and those containing gallium as a dopant (GZO) are used.
- the transparent conductive film most industrially used is indium oxide, and indium oxide containing tin as a dopant is called an ITO (Indium-Tin-Oxide) film, and a low resistance film is particularly easy. Has been widely used so far.
- a thin-film solar cell generally includes a transparent conductive film, one or more semiconductor thin-film photoelectric conversion units, and a back electrode, which are sequentially stacked on a light-transmitting substrate. Since silicon materials are abundant, silicon-based thin-film solar cells using silicon-based thin films for photoelectric conversion units (light absorption layers) are quickly put into practical use, and research and development are being actively promoted. ing.
- the types of silicon-based thin-film solar cells are further diversified, and in addition to amorphous thin-film solar cells that use amorphous thin films such as amorphous silicon in the conventional light absorption layer, fine crystalline silicon is mixed in amorphous silicon.
- a microcrystalline thin-film solar cell using a microcrystalline thin film and a crystalline thin-film solar cell using a crystalline thin film made of crystalline silicon have been developed, and a hybrid thin-film solar cell in which these are laminated has been put into practical use.
- the photoelectric conversion unit or the thin film solar cell has an amorphous photoelectric conversion layer that occupies the main part regardless of whether the p-type and n-type conductive semiconductor layers contained therein are amorphous, crystalline, or microcrystalline.
- amorphous units or amorphous thin film solar cells those with a photoelectric conversion layer crystalline are referred to as crystalline units or crystalline thin film solar cells, and those with a photoelectric conversion layer microcrystalline are It is called a microcrystalline unit or a microcrystalline thin film solar cell.
- the transparent conductive film is used for the surface transparent electrode of the thin film solar cell, and in order to effectively confine the light incident from the translucent substrate side in the photoelectric conversion unit, the surface is usually fine. Many irregularities are formed.
- the transparent conductive film If the haze ratio can be increased and sufficient light confinement can be performed, a high short-circuit current density (Jsc) can be realized, and a thin film solar cell with high conversion efficiency can be manufactured.
- a transparent conductive film having a high degree of unevenness and a high haze ratio a metal oxide material mainly composed of tin oxide produced by a thermal CVD method is known as a transparent electrode for thin film solar cells. Generally used.
- the conductive semiconductor layer formed on the surface of the transparent conductive film is generally manufactured in a gas atmosphere containing hydrogen by a plasma CVD method. If the formation temperature is increased in order to include microcrystals in the conductive semiconductor layer, the reduction of the metal oxide is promoted by hydrogen present, and in the case of a transparent conductive film mainly composed of tin oxide, There is a loss of transparency due to reduction. If such a transparent conductive film with poor transparency is used, a thin film solar cell with high conversion efficiency cannot be realized.
- Non Patent Literature 1 discloses a reduction resistance on a transparent conductive film made of tin oxide having a high degree of unevenness formed by a thermal CVD method.
- a method of forming a thin zinc oxide film having a good thickness by sputtering is proposed. Since zinc oxide has a strong bond between zinc and oxygen and is excellent in hydrogen reduction resistance, it is disclosed that the transparency of the transparent conductive film can be kept high by using the above structure.
- Non-Patent Document 2 proposes a method of obtaining a transparent conductive film having a surface roughness and having a high haze ratio, mainly composed of zinc oxide, by a sputtering method.
- a zinc oxide sintered body target to which 2 wt% of Al 2 O 3 is added is used for sputtering film formation at a high gas pressure of 3 to 12 Pa and a substrate temperature of 200 to 400 ° C.
- the film is formed by applying a power of DC 80 W to a 6 inch ⁇ target, and the input power density to the target is as extremely low as 0.442 W / cm 2 .
- Non-Patent Document 3 after obtaining a transparent conductive film with zinc oxide as a main component and produced by a conventional sputtering method and having small surface irregularities, the surface of the film is etched with acid to make the surface irregular.
- a method for producing a transparent conductive film having a high haze ratio is disclosed.
- this method after a film is manufactured by a sputtering method which is a vacuum process in a dry process, it is dried by performing acid etching in the air, and a semiconductor layer must be formed again by a CVD process in the dry process. There are problems such as complicated processes and high manufacturing costs.
- the present applicant has proposed a sputter target in which gallium oxide is mixed with zinc oxide as a main component and abnormal discharge is reduced by adding a third element (Ti, Ge, Al, Mg, In, Sn).
- a third element Ti, Ge, Al, Mg, In, Sn.
- the GZO sintered body containing gallium as a dopant has a ZnO phase in which 2 wt% or more of Ga and at least one selected from the group consisting of Ti, Ge, Al, Mg, In, and Sn are dissolved.
- the main constituent phase of the structure is the ZnO phase in which at least one of the above-mentioned elements is not dissolved in the other constituent phases, or an intermediate compound phase represented by ZnGa 2 O 4 (spinel phase).
- the present applicant optimizes the contents of aluminum and gallium in an oxide sintered body containing zinc oxide as a main component and further containing aluminum and gallium as additive elements.
- an oxide sintered body containing zinc oxide as a main component and further containing aluminum and gallium as additive elements By optimally controlling the type and composition of the crystal phase produced during firing, especially the spinel crystal phase composition, particles are less likely to form even if the film is formed continuously for a long time with a sputtering device, even under high DC power input.
- a target oxide sintered body that does not cause any abnormal discharge was proposed (see Patent Document 3). If this is used, it is possible to form a high-quality transparent conductive film having lower resistance and higher permeability than before, and therefore, it can be applied to the production of solar cells with high conversion efficiency. However, in recent years, a solar cell with higher conversion efficiency has been demanded, and a high-quality transparent conductive film that can be used therefor is required.
- the present invention uses a transparent conductive film excellent in hydrogen reduction resistance and excellent in light confinement effect, which is useful when manufacturing a highly efficient silicon-based thin film solar cell.
- An object of the present invention is to provide a transparent conductive film laminate and a method for producing the same, and a silicon-based thin film solar cell using the transparent conductive film or the transparent conductive film laminate as an electrode.
- the main component is one or more selected from aluminum or gallium as an additive metal element, the aluminum content [Al] and the gallium content [Ga] are within a specific range, and the surface roughness (Ra ) Is 35.0 nm or more and the surface resistance is 65 ⁇ / ⁇ or less, it was found that the zinc oxide-based transparent conductive film is excellent in hydrogen reduction resistance and excellent in light confinement effect.
- the transparent conductive film can be formed at high speed only by the sputtering method, and excellent in hydrogen reduction resistance, It has been found that a transparent conductive film having surface irregularities and having a high haze ratio and high conductivity can be obtained, and the present invention has been completed.
- zinc oxide is a main component, and one or more additive metal elements selected from aluminum or gallium are included, and the content is represented by the following formula (1).
- a transparent conductive film having a surface roughness (Ra) of 35.0 nm or more and a surface resistance of 65 ⁇ / ⁇ or less is provided.
- Ra surface roughness
- a transparent conductive film characterized in that, in the first invention, the haze ratio is 8% or more.
- the transparent conductive film according to the first aspect wherein the haze ratio is 10% or more.
- the transparent conductive film according to any one of the first to fourth aspects wherein the surface resistance is 20 ⁇ / ⁇ or less.
- the transparent conductive film according to the fifth aspect wherein the surface resistance is 15 ⁇ / ⁇ or less.
- oxide sintering containing zinc oxide as a main component and at least one additional metal element selected from aluminum or gallium is provided.
- a method for producing a transparent conductive film in which a zinc oxide-based transparent conductive film (II) is formed on a substrate by sputtering using a body target, wherein the sputtering gas pressure is 2.0 to 15.0 Pa and the substrate temperature is Provided is a method for producing a transparent conductive film, characterized by forming a film at a high speed under a condition of 200 to 500 ° C. with a DC input power density to the oxide sintered compact target being 1.66 W / cm 2 or more.
- a zinc oxide-based transparent conductive film (I) is formed on the indium oxide-based transparent conductive film (I) formed on the substrate.
- a transparent conductive film laminate characterized in that II) is formed is provided.
- the transparent conductive film (II) is a crystal film containing a hexagonal crystal phase.
- the hexagonal crystal phase has a substantially c-axis orientation, and the c-axis tilt angle is 10 with respect to a direction perpendicular to the substrate surface.
- the indium oxide-based transparent conductive film (I) contains indium oxide as a main component and is selected from Sn, Ti, W, Mo, or Zr.
- a transparent conductive film laminate is provided that is a crystalline film containing one or more metal elements.
- the indium oxide-based transparent conductive film (I) contains indium oxide as a main component and contains Sn, and the content ratio is Sn.
- the indium oxide-based transparent conductive film (I) contains indium oxide as a main component and contains Ti, and the content ratio is Ti.
- the atomic ratio is 5.5 atomic% or less, and a transparent conductive film laminate is provided.
- the indium oxide-based transparent conductive film (I) contains indium oxide as a main component and contains W, and the content ratio is W
- a transparent conductive film laminate is provided that has a / (In + W) atomic ratio of 4.3 atomic% or less.
- the indium oxide-based transparent conductive film (I) contains indium oxide as a main component and contains Zr, and the content ratio is Zr. / (In + Zr) The atomic number ratio is 6.5 atomic% or less, and a transparent conductive film laminate is provided.
- the indium oxide-based transparent conductive film (1) contains indium oxide as a main component and contains Mo, and the content ratio is Mo. / (In + Mo) The atomic ratio of 6.7 atomic% or less is provided.
- the transparent conductive film laminate according to any one of the eighth to sixteenth aspects wherein the surface resistance is 20 ⁇ / ⁇ or less.
- the transparent conductive film laminate according to the eighth to seventeenth aspects wherein the haze ratio is 12% or more.
- indium oxide containing one or more metal elements selected from Sn, Ti, W, Mo, or Zr A crystalline film of an indium oxide-based transparent conductive film (I) is formed on a substrate by a sputtering method using an oxide sintered body target containing as a main component, and then containing zinc oxide as a main component, aluminum or Switching to an oxide sintered compact target containing one or more additive metal elements selected from gallium, forming a zinc oxide-based transparent conductive film (II) on the indium oxide-based transparent conductive film (I)
- the manufacturing method of the transparent conductive film laminated body characterized by the above is provided.
- the indium oxide-based transparent conductive film (I) has a substrate temperature of 100 ° C. or lower and a sputtering gas pressure of 0.1 to 1.0 Pa.
- a method for producing a transparent conductive film laminate characterized in that after being formed as an amorphous film, it is subsequently heat-treated at 200 to 400 ° C. and crystallized.
- the indium oxide-based transparent conductive film (I) is subjected to a substrate temperature of 200 to 400 ° C. and a sputtering gas pressure of 0.1 to 1.0 Pa.
- a method for producing a transparent conductive film laminate, which is formed as a crystalline film, is provided.
- the transparent conductive film according to any one of the first to sixth inventions or the transparent conductive film according to any one of the eighth to seventeenth inventions is formed on the translucent substrate.
- a film laminate is formed, and at least one unit selected from the one conductive semiconductor layer unit, the photoelectric conversion layer unit, or the other conductive semiconductor layer unit is formed on the transparent conductive film or the transparent conductive film laminate.
- a silicon-based thin film solar cell is provided in which the back electrode layer is disposed on the unit.
- zinc oxide is the main component, and as the additive metal element other than zinc, a specific amount of one or more additive metal elements selected from aluminum or gallium is included, and the surface roughness (Ra) is 35. Since the surface resistance is 0 nm or more and the surface resistance is 65 ⁇ / ⁇ or less, it is possible to provide a transparent conductive film that is excellent in hydrogen reduction resistance, has surface irregularities, and has both a high haze ratio and high conductivity. And since this transparent conductive film can be manufactured only by sputtering method, it is excellent for the surface transparent electrode of a thin film solar cell, and is industrially useful.
- a transparent conductive film laminate in which the transparent conductive film is laminated on another transparent conductive film having a lower resistance, a surface transparent electrode of a thin film solar cell having a lower resistance can be obtained.
- the laminate can be provided at a lower cost than a transparent conductive film formed by a conventional thermal CVD method. Therefore, since a highly efficient silicon-based thin film solar cell can be provided at a low cost by a simple process, it is extremely useful industrially.
- FIG. 1 is an explanatory diagram showing a schematic configuration of a silicon-based thin film solar cell of the present invention using an amorphous silicon thin film as a photoelectric conversion unit.
- FIG. 2 is an explanatory diagram showing a schematic configuration of a silicon-based hybrid thin film solar cell of the present invention in which an amorphous silicon thin film and a crystalline silicon thin film are stacked as a photoelectric conversion unit.
- FIG. 3 is a graph showing the relationship between the contents of aluminum and gallium in the transparent electrode film of the present invention.
- FIG. 4 is a surface SEM photograph of the transparent conductive thin film obtained by the production method of the present invention.
- the transparent conductive film of the present invention contains zinc oxide as a main component, contains one or more additive metal elements selected from aluminum or gallium, and the content thereof is represented by the following formula (1).
- the surface roughness (Ra) is 35.0 nm or more, and the surface resistance is 65 ⁇ / ⁇ or less.
- the aluminum content [Al] and the gallium content [Ga] are in the relationship represented by the formula (1), and the composition is not within the shaded area in FIG. Don't be. If the content of aluminum and gallium in the transparent conductive film is larger than the range defined by the formula (1), aluminum and gallium are easily diffused into the silicon thin film formed on the transparent conductive film, There arises a problem that an excellent silicon-based thin film solar cell cannot be realized. Also, in terms of productivity, when the content of aluminum and gallium in the transparent conductive film is larger than the range defined by the formula (1), a transparent conductive film having a large surface irregularity and a high haze ratio is obtained by a sputtering method. It becomes impossible to manufacture at high speed. On the other hand, when the amount is less than the range defined by the formula (1), the conductivity is insufficient and the surface transparent electrode of the solar cell cannot be used.
- the surface roughness (Ra) of the transparent conductive film of the present invention is 35.0 nm or more.
- the surface roughness (Ra) is less than 35.0 nm, a zinc oxide-based transparent conductive film having a high haze ratio cannot be obtained, and when a silicon-based thin film solar cell is produced, the light confinement effect is inferior and high conversion efficiency. Cannot be realized.
- Ra is preferably as large as possible at 35.0 nm or more.
- Non-Patent Document 2 a film having a large amount of Al and having surface irregularities can be formed only at a low speed. When the film is formed at a high speed, the surface irregularity is lowered. The shape of the surface irregularities is not as desired when performed at high speed.
- the surface resistance of the transparent conductive film of the present invention needs to be 65 ⁇ / ⁇ or less. If it exceeds 65 ⁇ / ⁇ , when used as a surface electrode of a solar cell, power loss at the surface electrode increases, and a highly efficient solar cell cannot be realized.
- the transparent conductive film of the present invention can be made 65 ⁇ / ⁇ or less by using the film composition as described above.
- the surface resistance of the zinc oxide-based transparent conductive film of the present invention is preferably 20 ⁇ / ⁇ or less, more preferably 15 ⁇ / ⁇ or less. As the surface resistance of the zinc oxide-based transparent conductive film used for the surface electrode is lower, the power loss at the surface electrode portion is smaller, so that a highly efficient solar cell can be realized even with a large cell area.
- the surface electrode has a high surface resistance, if the solar cell is large, the power loss at the surface electrode increases to a level that cannot be ignored. It is necessary to increase the area by wiring small cells. If the surface electrode is 65 ⁇ / ⁇ or less, a solar cell of at least 5 cm ⁇ can be realized, but if it is 20 ⁇ / ⁇ or less, it is at least 8 cm ⁇ solar cell, and if it is 15 ⁇ / ⁇ or less, it is at least 12 cm ⁇ . The cell can be realized without considering the effect of power loss at the surface electrode. Solar cells with a small cell area need to be connected by metal wiring, which not only reduces the power generation per unit area of one module made by connecting cells due to factors such as increased cell spacing. This is not preferable because of problems such as an increase in manufacturing cost per cell area.
- the haze ratio of the zinc oxide-based transparent conductive film of the present invention is preferably 8% or more. As described above, since the surface roughness Ra of the zinc oxide-based transparent conductive film of the present invention is 35.0 nm or more, a haze ratio of 8% or more can be realized.
- the haze ratio is preferably 10% or more, more preferably 16% or more. The higher the haze ratio, the better the light confinement effect, so that a highly efficient solar cell can be realized. This can be achieved by forming a zinc oxide-based transparent conductive film under the sputtering conditions described later.
- the zinc oxide-based transparent conductive film of the present invention is a transparent conductive film that is excellent in hydrogen reduction resistance, has surface irregularities, has a high haze ratio and high conductivity, and can be produced only by a sputtering method. Therefore, it is excellent as a transparent conductive film for a surface transparent electrode of a thin film solar cell.
- the method for producing a zinc oxide-based transparent conductive film of the present invention comprises an oxide sintered body containing zinc oxide as a main component and at least one additional metal element selected from aluminum or gallium.
- the film is formed at a high speed under a condition of ⁇ 500 ° C. with a DC input power density to the oxide sintered compact target being 1.66 W / cm 2 or more.
- the target is an oxide sintered body containing zinc, aluminum and gallium, and the content of aluminum and gallium is within the range represented by the following formula (1).
- the surface roughness as described above is large and the zinc oxide-based transparent material of the present invention having a high haze ratio is used.
- the conductive film can be manufactured at high speed by a sputtering method.
- the content of aluminum and gallium is larger than within the range of the formula (1) (a range on the upper right side of the shaded area in FIG. 3)
- a film with large surface irregularities cannot be obtained at high speed by the sputtering method.
- it is less than the range defined by the formula (1) lower left region of the shaded area in FIG. 3
- the surface transparent electrode of the solar cell Can not be used as. If the amount of a high melting point substance such as aluminum oxide or gallium oxide increases with respect to zinc oxide, the crystal growth of the film during film formation slows down. In this way, the unevenness caused by crystal growth does not increase. If aluminum and gallium have the above composition, even with high-speed film formation with a high input power of 1.66 W / cm 2 or more, it is possible to obtain a film with large surface irregularities due to large crystal grains. is there.
- This oxide sintered body is prepared by adding and mixing a gallium oxide powder and an aluminum oxide powder to a zinc oxide powder as a raw material powder, and subsequently grinding and pulverizing a slurry obtained by adding an aqueous medium to the raw material powder.
- the oxide sintered body includes other elements (for example, indium, titanium, tungsten, molybdenum, iridium, ruthenium, rhenium, cerium, magnesium, silicon, fluorine, etc.) However, it may be included as long as the object of the present invention is not impaired.
- a zinc oxide transparent conductive film having a high surface roughness and a high haze ratio is formed at a high speed with a sputtering gas pressure of 2.0 to 15.0 Pa and a substrate temperature of 200 to 500 ° C. Can do.
- To form a film at a high speed means to perform sputtering film formation by increasing the input power to the target to 1.66 W / cm 2 or more. Accordingly, for example, a zinc oxide-based transparent conductive film having a large surface roughness and a high haze ratio can be obtained even when a film formation rate of 40 nm / min or more is performed in the stationary facing film formation.
- Non-Patent Document 2 when a target having a target composition: Al / (Zn + Al) exceeding 3 atomic% as used in Non-Patent Document 2 is used, surface irregularity is increased when the input power is increased and the film is formed at a high speed. Only films that are poor and have a low haze ratio can be produced. Further, even when a target having a target composition of Ga / (Zn + Ga) exceeding 2 atomic% is used, if a film is formed at a high speed by increasing the input power, only a film having a low surface roughness and a low haze ratio can be obtained. .
- the present invention can also be applied to transport film formation (passage film formation).
- (nm) the film thickness obtained by dividing by 3.5 nm ⁇ m / min (conveying speed (m / min)) at the same input power density.
- (nm) the film-forming speed
- the present invention can be applied to planar magnetron type sputtering film formation with a flat target, and can also be applied to rotary magnetron type sputtering film formation using a cylindrical target.
- the sputtering gas pressure is less than 2.0 Pa, it is difficult to obtain a film having large surface irregularities, and a film having an Ra value of 35.0 nm or more cannot be obtained. On the other hand, if it exceeds 15.0 Pa, the film formation rate is slow, which is not preferable.
- the sputtering gas pressure is 15. Must be 0 Pa or less.
- the conductivity of the zinc oxide-based transparent conductive film greatly depends on the substrate heating temperature during film formation. This is because when the substrate heating temperature is high, the crystallinity of the film is improved and the mobility of carrier electrons is increased.
- the substrate is preferably heated to 200 to 500 ° C., particularly 300 to 500 ° C.
- the film is formed by heating the substrate to a high temperature, the crystallinity of the obtained transparent conductive film is improved, and excellent conductivity can be realized due to the above-mentioned factors. * Changed to 500 ° C
- the transparent electrically conductive film of this invention can be used as a laminated body of a transparent electrically conductive film for the surface electrodes of a lower resistance thin film solar cell.
- the above-described zinc oxide-based transparent conductive film (II) is formed on the surface of the indium oxide-based transparent conductive film (I) formed on the translucent substrate.
- the zinc oxide-based transparent conductive film (II) contains zinc oxide as a main component and contains one or more additive metal elements selected from aluminum or gallium,
- the gallium content is within the range represented by the following formula (1). — [Al] + 0.30 ⁇ [Ga] ⁇ ⁇ 2.68 ⁇ [Al] +1.74 (1) (However, [Al] is the aluminum content expressed by the atomic ratio (%) of Al / (Zn + Al), while [Ga] is expressed by the atomic ratio (%) of Ga / (Zn + Ga).
- Gallium content When the content of aluminum and gallium in the zinc oxide-based transparent conductive film is larger than the range defined by the formula (1), aluminum and gallium are easily diffused into the silicon-based thin film formed thereon, and the characteristics are excellent. Silicon thin film solar cells cannot be realized. Also in terms of productivity, when the aluminum and gallium contents in the film are larger than the range defined by the formula (1), a transparent conductive film having large surface irregularities and a high haze ratio is produced at high speed by the sputtering method. I can't. On the other hand, when the amount is less than the range defined by the formula (1), the conductivity is insufficient and the surface transparent electrode of the solar cell cannot be used.
- the surface roughness (Ra) of the zinc oxide-based transparent conductive film of the present invention is preferably 35.0 nm or more.
- the surface roughness (Ra) is less than 35.0 nm, a zinc oxide-based transparent conductive film having a high haze ratio cannot be obtained, and when a silicon-based thin film solar cell is produced, the light confinement effect is inferior and high conversion efficiency. Cannot be realized.
- the surface roughness (Ra) is preferably as large as possible at 35.0 nm or more.
- the surface roughness (Ra) of the transparent conductive film exceeds 70 nm, the growth of the silicon-based thin film formed on the transparent conductive film is affected, and a gap is formed at the interface between the transparent conductive film and the silicon-based thin film. Occurs, the contact property deteriorates and the solar cell characteristics deteriorate, which is not preferable.
- the surface resistance of the transparent conductive film laminate of the present invention is 65 ⁇ / ⁇ or less. When the surface resistance exceeds 65 ⁇ / ⁇ , when used as a surface electrode of a solar cell, power loss at the surface electrode increases, and a highly efficient solar cell cannot be realized. Since the transparent conductive film laminate of the present invention has the laminated structure as described above, the surface resistance can be set to 65 ⁇ / ⁇ or less.
- the surface resistance of the transparent conductive film laminate of the present invention is preferably 20 ⁇ / ⁇ or less, more preferably 13 ⁇ / ⁇ or less, still more preferably 10 ⁇ / ⁇ or less, and most preferably 8 ⁇ / ⁇ or less.
- Such a surface resistance can be realized because the indium oxide-based transparent conductive film having the above characteristics is inserted into the base.
- the zinc oxide-based transparent conductive film used for the surface electrode is preferable as the surface resistance is low, because the power loss at the surface electrode portion is small, so that a highly efficient solar cell can be realized even with a large cell area.
- the surface resistance of the surface electrode is high, the power loss at the surface electrode increases to a level that cannot be ignored when the solar cell is large, so the cell area is reduced and many metal wires with low resistance are used. It is necessary to increase the area by wiring small cells.
- the surface electrode is 65 ⁇ / ⁇ or less, a solar cell of at least 5 cm ⁇ can be realized, but if it is 20 ⁇ / ⁇ or less, a solar cell of at least 8 cm ⁇ can be realized, and if it is 13 ⁇ / ⁇ or less, at least If the 15 cm ⁇ cell is 10 ⁇ / ⁇ or less, at least 17 cm ⁇ cell can be realized, and if it is 8 ⁇ / ⁇ or less, at least 20 cm ⁇ cell can be realized without considering the influence of power loss at the surface electrode.
- Solar cells with a small cell area need to be connected by metal wiring, which not only reduces the power generation per unit area of one module made by connecting cells due to factors such as increased cell spacing. This is not preferable because of problems such as an increase in manufacturing cost per cell area.
- the haze ratio of the transparent conductive film laminate of the present invention is more preferably 12% or more, further preferably 16% or more, and most preferably 20% or more, and the light confinement effect is very high. Since the indium oxide-based transparent conductive film having the above characteristics is inserted in the base, such a high haze ratio can be realized.
- a haze ratio of 12% or more is indispensable in order to achieve a conversion efficiency of 10% or more. In order to realize a conversion efficiency of 12% or more in the same evaluation, it is effective to use a surface electrode having a haze ratio of 16% or more.
- a surface electrode having a haze ratio of 20% or more is particularly useful.
- the zinc oxide-based transparent conductive film (II) in the transparent conductive film laminate of the present invention is a crystal film containing a hexagonal crystal phase, and the c-axis tilt angle is 15 ° with respect to the vertical direction of the substrate.
- the material has an excellent substantially c-axis orientation of 10 ° or less.
- the present applicant has clarified that the c-axis of the film does not necessarily grow in the vertical direction of the substrate surface but is slightly inclined with respect to the vertical direction from the pursuit by X-ray pole figure measurement.
- the zinc oxide-based transparent conductive film (II) has an excellent substantially c-axis orientation in which the inclination angle with respect to the vertical direction of the c-axis substrate surface is 10 ° or less. High haze rate can be achieved.
- the degree of inclination of the c-axis of the zinc oxide-based transparent conductive film (II) of the transparent conductive film laminate as in the present invention greatly depends on the manufacturing conditions of the underlying indium oxide-based transparent conductive film (I). .
- the indium oxide-based transparent conductive film (I) In order for the transparent conductive film laminate of the present invention to become a lower resistance transparent conductive film laminate, the indium oxide-based transparent conductive film (I) must be used as the base of the zinc oxide-based transparent conductive film (II). Don't be. That is, the indium oxide-based transparent conductive film (I) is a crystal film containing indium oxide as a main component and at least one metal element selected from Sn, Ti, W, Mo, or Zr. A crystal film in which an additive element of Sn, Ti, W, Mo, or Zr is included in indium oxide is useful because of its excellent conductivity. In particular, when an element of Ti, W, Mo, or Zr is included, a film with high mobility can be obtained. Therefore, since the resistance is reduced without increasing the carrier concentration, a low resistance film having a high transmittance in the visible region to the near infrared region can be realized.
- the content ratio is preferably 15 atomic% or less in terms of the Sn / (In + Sn) atomic ratio, and in the case of containing Ti, the content ratio is Ti / ( In + Ti) atomic ratio is preferably 5.5 atomic% or less, and when W is contained, its content is preferably 4.3 atomic% or less in terms of W / (In + W) atomic ratio, Zr
- the content ratio is preferably 6.5 atomic percent or less in terms of the Zr / (In + Zr) atomic ratio, and in the case of containing Mo, the content ratio is Mo / (In + Mo) atomic ratio. Is preferably 6.7 atomic% or less. If the content exceeds this range, the resistance becomes high, which is not useful.
- an indium oxide-based transparent conductive material is formed by a sputtering method using an oxide sintered body target composed mainly of indium oxide containing one or more metal elements selected from Sn, Ti, W, Mo, or Zr.
- a crystal film of film (I) is formed on the substrate, and then switched to an oxide sintered body target containing zinc oxide as a main component and containing one or more additional metal elements selected from aluminum or gallium.
- a zinc-based transparent conductive film (II) is formed on the indium oxide-based transparent conductive film (I).
- the indium oxide-based transparent conductive film (I) is formed by a first method in which an amorphous film is formed without heating the substrate and then crystallized by heat treatment, and a crystalline material is heated by heating the substrate.
- an amorphous film is formed under the conditions of a substrate temperature of 100 ° C. or lower and a sputtering gas pressure of 0.1 to 1.0 Pa, and subsequently heat-treated at 200 to 400 ° C.
- the film is crystallized to form an indium oxide-based transparent conductive film.
- an indium oxide-based transparent conductive film is formed as a crystal film under conditions of a substrate temperature of 200 to 400 ° C.
- a planar-type magnetron type sputtering film formation with a flat target can be applied as a planar-type magnetron type sputtering film formation with a flat target. Also, a rotary magnetron type sputtering film formation using a cylindrical target can be applied.
- the first method in which an amorphous film is formed without heating the substrate and then crystallized by heat treatment is more than the second method in which the crystalline film is formed by heating the substrate.
- the first method is used, a film having a larger surface roughness (Ra) and a higher haze ratio can be obtained. Since the transparent conductive film laminate obtained by such a production method has a high haze ratio and a low resistance value, it is useful for a surface electrode of a highly efficient solar cell.
- the thickness of the transparent conductive film is not particularly limited, and depends on the composition of the material, but the indium oxide-based transparent conductive film (I) has a thickness of 40 to 400 nm, particularly 45 to 300 nm.
- the zinc oxide-based transparent conductive film (II) has a thickness of 500 to 1700 nm, particularly preferably 700 to 1620 nm.
- the transparent conductive film of the present invention has a low resistance and a high transmittance of sunlight including visible light to near infrared light having a wavelength of 380 nm to 1200 nm. Therefore, the light energy of sunlight is extremely effectively converted into electric energy. be able to.
- the transparent conductive film or the transparent conductive film laminate is formed on a translucent substrate, and the transparent conductive film laminate or the transparent conductive film laminate is formed.
- at least one unit selected from one-conductivity-type semiconductor layer unit, photoelectric conversion layer unit, or other-conductivity-type semiconductor layer unit is disposed, and a back electrode layer is disposed on the unit.
- a thin film solar cell includes a transparent conductive film, one or more semiconductor thin film photoelectric conversion units, and a back electrode, which are sequentially stacked on a translucent substrate.
- One photoelectric conversion unit includes a p-type layer, an n-type layer, and an i-type layer sandwiched therebetween.
- the structure of this typical silicon-based amorphous thin film solar cell is shown in FIG.
- the p-type and n-type conductive semiconductor layers serve to generate an internal electric field in the photoelectric conversion unit, and an open circuit voltage (Voc) which is one of the important characteristics of the thin film solar cell depending on the magnitude of the internal electric field. The value of depends on.
- the i-type layer is a substantially intrinsic semiconductor layer and occupies most of the thickness of the photoelectric conversion unit, and the photoelectric conversion action mainly occurs in the i-type layer. For this reason, this i-type layer is usually called an i-type photoelectric conversion layer or simply a photoelectric conversion layer.
- the photoelectric conversion layer is not limited to an intrinsic semiconductor layer, and may be a layer doped in a small amount of p-type or n-type within a range where loss of light absorbed by a doped impurity (dopant) does not become a problem.
- the photoelectric conversion unit or the thin film solar cell is an amorphous unit or an amorphous thin film solar cell if the photoelectric conversion layer occupying the main part is amorphous, or the photoelectric conversion layer is crystalline.
- the ones are called crystalline units or crystalline thin film solar cells, and the ones whose photoelectric conversion layer is microcrystalline are called microcrystalline units or microcrystalline thin film solar cells.
- a method for improving the conversion efficiency of such a thin film solar cell there is a method of stacking two or more photoelectric conversion units into a tandem solar cell.
- a front unit including a photoelectric conversion layer having a large band gap is disposed on the light incident side of the thin film solar cell, and a rear unit including a photoelectric conversion layer having a small band gap is sequentially disposed behind the unit.
- the photoelectric conversion is enabled over a wide wavelength range of the incident light, thereby improving the conversion efficiency of the entire solar cell.
- tandem solar cells a typical structure of a hybrid thin film solar cell in which an amorphous photoelectric conversion unit and a crystalline or microcrystalline photoelectric conversion unit are stacked is shown in FIG.
- the wavelength range of light that can be photoelectrically converted by i-type amorphous silicon is up to about 800 nm on the long wavelength side, but i-type crystalline or microcrystalline silicon has a longer wavelength of about 1150 nm. Light up to a certain wavelength can be photoelectrically converted.
- the transparent conductive film of the present invention can be produced using only a sputtering method, has high productivity, is excellent in hydrogen reduction resistance, has surface irregularities, has a high haze ratio, and is so-called.
- a transparent conductive film having an excellent light confinement effect and a low resistance can be obtained.
- the transparent conductive film is made of another low resistance transparent conductive film, that is, an indium oxide-based transparent conductive film (I).
- stacked on it can be obtained.
- the silicon-type thin film solar cell which used this transparent conductive film or transparent conductive film laminated body as an electrode can be provided.
- the silicon-based thin film solar cell of the present invention has the above-described large surface unevenness, a high haze ratio and a low resistance zinc oxide-based transparent conductive film, or the transparent conductive film laminate, on which A silicon-based thin-film solar cell in which at least one set of a conductive semiconductor layer, a photoelectric conversion layer, and another conductive semiconductor layer is disposed, and a back electrode layer is disposed thereon.
- a zinc oxide-based transparent conductive film 2 of the present invention is formed on a translucent substrate 1.
- a translucent substrate 1 a plate-like member or a sheet-like member made of glass, transparent resin or the like is used.
- An amorphous photoelectric conversion unit 3 is formed on the transparent conductive film 2.
- the amorphous photoelectric conversion unit 3 includes an amorphous p-type silicon carbide layer 3p, a non-doped amorphous i-type silicon photoelectric conversion layer 3i, and an n-type silicon-based interface layer 3n.
- the amorphous p-type silicon carbide layer 3p is formed at a substrate temperature of 180 ° C. or lower in order to prevent a decrease in transmittance due to reduction of the transparent conductive film 2.
- a crystalline photoelectric conversion unit 4 is formed on the amorphous photoelectric conversion unit 3.
- the crystalline photoelectric conversion unit 4 includes a crystalline p-type silicon layer 4p, a crystalline i-type silicon photoelectric conversion layer 4i, and a crystalline n-type silicon layer 4n.
- a high-frequency plasma CVD method is suitable for forming the amorphous photoelectric conversion unit 3 and the crystalline photoelectric conversion unit 4 (hereinafter, both units are collectively referred to as a photoelectric conversion unit).
- the formation conditions of the photoelectric conversion unit include a substrate temperature of 100 to 250 ° C. (however, the amorphous p-type silicon carbide layer 3p is 180 ° C.
- a pressure of 30 to 1500 Pa, and a high frequency power density of 0.01 to 0.5 W / cm. 2 is preferably used.
- a silicon-containing gas such as SiH 4 or Si 2 H 6 or a mixture of these gases and H 2 is used.
- the dopant gas for forming the p-type or n-type layer in the photoelectric conversion unit B 2 H 6 or PH 3 is preferably used.
- a back electrode 5 is formed on the crystalline n-type silicon layer 4n of the interface layer.
- the back electrode 5 includes a back transparent electrode layer 5t and a back reflective electrode layer 5m.
- the back transparent electrode layer 5t may be a metal oxide according to the prior art such as ZnO or ITO, and Ag, Al or an alloy thereof is preferably used for the back reflective electrode layer 5m.
- a method such as sputtering or vapor deposition is preferably used.
- the back electrode 5 has a thickness of usually 0.5 to 5 ⁇ m, preferably 1 to 3 ⁇ m.
- the silicon-based thin-film solar cell of the present invention is completed by heating to near atmospheric pressure at an atmospheric temperature equal to or higher than the formation temperature of the amorphous p-type silicon carbide layer 3p.
- the gas used in the heating atmosphere air, nitrogen, a mixture of nitrogen and oxygen, or the like is preferably used.
- the vicinity of atmospheric pressure generally indicates a range of 0.5 to 1.5 atmospheres.
- the zinc oxide based transparent conductive film of the present invention is not limited by this example.
- the film thickness was measured by the following procedure. Before forming a film, apply a part of the substrate with oil-based magic ink, wipe the magic with ethanol after film formation, and form a film-free part. It was determined by measuring with a shape measuring instrument (Alpha-Step IQ manufactured by KLA Tencor). (2) The composition of the obtained transparent conductive thin film was quantitatively analyzed by ICP emission spectroscopic analysis (manufactured by Seiko Instruments Inc., SPS4000). (3) The crystallinity and orientation of the film were examined by X-ray diffraction measurement using an X-ray diffractometer (M18XHF22, manufactured by Mac Science) using CuK ⁇ rays.
- X-ray diffractometer M18XHF22, manufactured by Mac Science
- each transparent conductive thin film was measured by a four-probe method using a resistivity meter Loresta EP (Model MCP-T360 manufactured by Dia Instruments).
- the total light transmittance and parallel line transmittance including the substrate, and the total light reflectance and parallel light reflectance were measured with a spectrophotometer (manufactured by Hitachi, Ltd., U-4000).
- the haze ratio of the film was evaluated with a haze meter (HM-150 manufactured by Murakami Color Research Laboratory Co., Ltd.) based on JIS standard K7136.
- the surface roughness (Ra) of the film was measured in an area of 5 ⁇ m ⁇ 5 ⁇ m using an atomic force microscope (manufactured by Digital Instruments, NS-III, D5000 system).
- Example 3 Using a zinc oxide sintered compact target containing aluminum as an additive element (manufactured by Sumitomo Metal Mining), a zinc oxide-based transparent conductive film having large surface irregularities was produced as follows.
- the composition of the target used was quantitatively analyzed by ICP emission spectroscopic analysis (manufactured by Seiko Instruments Inc., SPS4000), and as shown in Table 1, Al / (Zn + Al) was 0.30 to 0.65 atomic%.
- the purity of each target is 99.999%, and the size of the target is 6 inches ( ⁇ ) ⁇ 5 mm (thickness).
- This sputtering target is applied to a cathode for a ferromagnetic target of a DC magnetron sputtering apparatus (SPF503K, manufactured by Tokki Co., Ltd.) (maximum horizontal magnetic field strength at a position 1 cm away from the target surface is about 80 kA / m (1 kG)).
- SPF503K DC magnetron sputtering apparatus
- maximum horizontal magnetic field strength at a position 1 cm away from the target surface is about 80 kA / m (1 kG)
- a Corning 7059 glass substrate having a thickness of 1.1 mm was attached to the opposite surface of the sputtering target.
- the average light transmittance of the Corning 7059 glass substrate itself in the visible light wavelength region is 92%.
- the distance between the sputtering target and the substrate was 50 mm.
- the inside of the chamber was evacuated, and when the degree of vacuum reached 2 ⁇ 10 ⁇ 4 Pa or less, Ar gas having a purity of 99.9999 mass% was introduced into the chamber, and the gas pressure was set to 3.0 Pa. It was.
- the film formation rate was as fast as 68 to 70 nm / min.
- the film thickness, composition, crystallinity, orientation of the film, and specific resistance of each transparent conductive thin film were measured by the above methods. Further, the total light transmittance and parallel line transmittance including the substrate, the total light reflectance and parallel light reflectance, and the haze ratio of the film were measured by the above methods. Table 1 shows the characteristics of the films obtained in Examples 1 to 3.
- the composition of the obtained film was almost the same as that of the target.
- the film thickness was 830 to 850 nm.
- FIG. 4 shows a surface SEM photograph of the film of Example 2. It can be seen that the film is composed of large grains and has a large surface irregularity. It has been confirmed that the surfaces of the membranes of Examples 1 and 3 have the same structure. The surface resistance was 43 to 63 ⁇ / ⁇ , indicating high conductivity. Therefore, Examples 1 to 3 confirmed that a zinc oxide-based transparent conductive film having a high haze ratio and excellent conductivity could be obtained at high speed.
- a zinc oxide-based transparent conductive film was produced from a zinc oxide sintered compact target containing aluminum in the same manner as in Examples 1 to 3, except that the target composition was changed.
- the target those having the composition Al / (Zn + Al) of 1.59 atomic% (Comparative Example 1), 0.80 atomic% (Comparative Example 2), and 0.20 atomic% (Comparative Example 3) were used. .
- the conditions were the same as in Examples 1 to 3.
- the properties of the obtained film are shown in Table 1. The composition of the obtained film was almost the same as that of the target.
- Example 6 Using a zinc oxide sintered compact target containing gallium as an additive element, a zinc oxide-based transparent conductive film having large surface irregularities was produced.
- a zinc oxide based transparent conductive film was produced under the same conditions as in Examples 1 to 3, except that the sintered compact target was used and the gas pressure was 8.0 Pa and the substrate temperature was 300 ° C.
- the obtained film was evaluated in the same manner as in Examples 1 to 3. Table 1 shows the conditions for producing the film and the characteristics of the obtained film.
- the composition of the obtained film was almost the same as the composition of the target.
- the films of Examples 4 to 6 were formed with a film thickness of 780 to 800 nm at a high speed of about 71 nm / min.
- the Ra values of the films were all as large as 48 to 56 nm and the haze ratio was 10
- the surface resistance was as high as 8 to 12.1%, and the surface resistance was high within the range of 11 to 25 ⁇ / ⁇ . Therefore, such a film can be used for a surface transparent electrode of a solar cell having an excellent light confinement effect.
- a zinc oxide-based transparent conductive film was produced from a zinc oxide sintered compact target containing gallium in the same manner as in Examples 4 to 6, but the target composition Ga / (Zn + Ga) was 3.48 atomic% (Comparative Example 4). Targets of 62 atomic% (Comparative Example 5) and 0.20 atomic% (Comparative Example 6) were used.
- a zinc oxide-based transparent conductive film was produced under the same conditions as in Examples 4 to 6 except for the target composition. Since the input power density to the target during film formation is 2.210 W / cm 2 which is the same as in Examples 1 to 3, a high film formation speed of 70 to 72 nm / min is obtained. The obtained film was evaluated in the same manner as in Examples 1 to 3.
- the properties of the obtained film are shown in Table 1.
- the film composition was almost the same as the target composition.
- the films of Comparative Examples 4 and 5 had good conductivity, but unlike Examples 4 to 6, the films had low Ra values and low haze ratios. Therefore, since the light confinement effect is insufficient, it cannot be used as a surface transparent electrode of a highly efficient solar cell.
- membrane of the comparative example 6 has high Ra value and a haze rate, since surface resistance is too high, it cannot be utilized as an electrode of a solar cell.
- Example 7 to 10 Using a zinc oxide sintered compact target containing aluminum and gallium as additive elements, a zinc oxide-based transparent conductive film having large surface irregularities was produced. The same conditions as in Examples 1 to 3 except that the zinc oxide sintered compact target containing aluminum and gallium shown in the target composition of Table 1 was used, the gas pressure was 5.0 Pa, and the substrate temperature was 350 ° C. A zinc oxide-based transparent conductive film was produced. The obtained film was evaluated in the same manner as in Examples 1 to 3. Table 1 shows the conditions for producing the film and the characteristics of the obtained film. The composition of the film was almost the same as the target composition.
- the films of Examples 7 to 10 were films having a film thickness of 824 to 851 nm and were formed at a high speed of about 69 nm / min.
- the Ra values of the films were all as large as 38 to 50 nm and the haze ratio was 8.
- the surface resistance was as high as 5 to 12.1%, and the surface resistance was high in the range of 29 to 57 ⁇ / ⁇ . Therefore, such a film
- membrane can be utilized for the surface transparent electrode of the solar cell excellent in the light confinement effect.
- a zinc oxide-based transparent conductive film was prepared from a zinc oxide sintered compact target containing aluminum and gallium in the same manner as in Examples 7 to 10, but as shown in Table 1, a target having a composition deviating from the composition range of the present invention was used. It was.
- a zinc oxide-based transparent conductive film was produced under the same conditions as in Examples 7 to 10 except for the target composition. Since the input power density to the target during film formation is 2.210 W / cm 2, which is the same as in Examples 7 to 10, a high film formation rate of 66 to 70 nm / min is obtained. The obtained film was evaluated in the same manner as in Examples 1 to 3. The properties of the obtained film are shown in Table 1. The composition of the film was almost the same as the target composition.
- the films of Comparative Examples 7 and 8 had good electrical conductivity, but unlike Examples 7 to 10, the Ra value was low and the haze ratio was low. Therefore, since the light confinement effect is insufficient, it cannot be used as a surface transparent electrode of a highly efficient solar cell. Moreover, although the film
- a zinc oxide-based transparent conductive film was produced from a zinc oxide sintered compact target containing aluminum in the same manner as in Examples 1 to 3, but a target having a target composition Al / (Zn + Al) of 3.16 atomic% was used. A target having this composition is also used in Non-Patent Document 2. The power density applied to the target during film formation was changed within the range of 0.442 to 2.210 W / cm 2 . Except for the target composition and input power, the films were formed under the same conditions as in Examples 1 to 3, and a zinc oxide-based transparent conductive film having a film composition Al / (Zn + Al) of 3.18 atomic% was produced. The characteristics of the obtained film were evaluated in the same manner as in Examples 1 to 3.
- the film forming conditions and the characteristics of the obtained film are shown in Table 1.
- the film formation rate increased.
- Comparative Example 10 when a low power input of 0.442 W / cm 2 was applied to the target, a transparent conductive film having a high Ra value and a high haze ratio and satisfactory conductivity was obtained. The same result was obtained.
- Comparative Example 10 since the input power density is low, the film formation rate is extremely slow, which is not practical.
- Comparative Examples 11 to 13 are examples in which the input power density was further increased. However, the haze ratio was remarkably reduced as the input power density was increased, and the haze ratio was 1.105 W / cm 2 (Comparative Example 11). A high film is not obtained.
- a zinc oxide-based transparent conductive film was produced from a zinc oxide sintered compact target containing gallium.
- a target having a target composition Ga / (Zn + Ga) of 4.99 atomic% was used, the film forming gas pressure was 8.3 Pa, and the power density applied to the target during film formation was 0.442 to 2.210 W / cm 2 .
- the film formation was performed under the same conditions as in Examples 4 to 6 except that the range was changed.
- a zinc oxide-based transparent conductive film having a film composition Ga / (Zn + Ga) of 5.03 atomic% is obtained. The characteristics of the obtained film were evaluated in the same manner as in Examples 1 to 3.
- the film forming conditions and the characteristics of the obtained film are shown in Table 1. As the power density applied to the target during film formation increased, the film formation rate increased, and the Ra value and haze ratio of the film tended to decrease. However, a film having a high haze ratio that can be used as a surface transparent electrode of a solar cell was not obtained at any input power density.
- Examples 11 to 13, Comparative Example 18 In the same manner as in Examples 4 to 6, a zinc oxide-based transparent conductive film was produced from a zinc oxide sintered compact target containing gallium. A target having a target composition Ga / (Zn + Ga) of 1.31 atomic% was used, the film forming gas pressure was 5.5 Pa, the power density applied to the target was 2.760 W / cm 2 , and the film forming time was changed. Zinc oxide-based transparent conductive films having a thickness of 830 nm (Comparative Example 18), 1010 nm (Example 11), 1350 nm (Example 12), and 1620 nm (Example 13) were produced. The characteristics of the obtained film were evaluated in the same manner as in Examples 1 to 3.
- the film forming conditions and the characteristics of the obtained film are shown in Table 1.
- the film composition of Ga / (Zn + Ga) was 1.35 atomic% and was almost the same as the target composition.
- the surface resistance decreased, but the Ra value and haze ratio also increased.
- the film of Comparative Example 18 has a low surface resistance and is sufficient, but has a low haze ratio and a weak light confinement effect, and cannot be used as a surface transparent electrode of a highly efficient solar cell.
- the films of Examples 11 to 13 have not only low surface resistance but also a sufficiently high haze ratio of 8% or more, they can be used as surface transparent electrodes for highly efficient solar cells.
- Examples 14 to 16, Comparative Examples 19 to 20 In the same manner as in Examples 7 to 10, a zinc oxide-based transparent conductive film was produced from a zinc oxide sintered compact target containing aluminum and gallium.
- the target composition is such that Ga / (Zn + Ga) is 0.28 atomic%, Al / (Zn + Al) is 0.28 atomic%, the power density applied to the target is 1.660 W / cm 2 , and the substrate temperature is 300 ° C.
- the gas pressure was changed to 1.0 Pa (Comparative Example 19), 2.0 Pa (Example 14), 10.5 Pa (Example 15), 15.0 Pa (Example 16), 20.0 Pa (Comparative Example)
- a zinc oxide-based transparent conductive film was produced at each gas pressure of 20).
- the film formation time was adjusted in consideration of the film formation rate at each gas pressure, and the same zinc oxide-based transparent conductive film with a film thickness of 1340 to 1360 nm was produced.
- the characteristics of the obtained film were evaluated in the same manner as in Examples 1 to 3.
- the film forming conditions and the characteristics of the obtained film are shown in Table 1.
- the film composition was almost the same as the target composition.
- the Ra value and the haze ratio increased.
- the film of Comparative Example 19 has a low haze ratio and a weak light confinement effect, and cannot be used as a surface transparent electrode of a highly efficient solar cell.
- Comparative Example 20 the film formation rate at the time of production was very slow and the productivity was poor, and the obtained film had a high haze ratio but a high surface resistance, and the adhesion of the film to the substrate was weak. It is easy to peel off and cannot be used as a device electrode.
- the films of Examples 14 to 16 not only have low surface resistance, but also have a sufficiently high haze ratio of 8% or more and high adhesion of the film, so that they can be used as surface transparent electrodes for highly efficient solar cells. .
- Example 17 Comparative Examples 21 to 22
- a zinc oxide-based transparent conductive film was produced from a zinc oxide sintered compact target containing gallium.
- the target composition is Ga / (Zn + Ga) of 0.30 atomic%
- the input power density to the target is 2.760 W / cm 2
- the gas pressure is 6.0 Pa
- the substrate temperature is changed to 150 ° C.
- Example 21 A zinc oxide-based transparent conductive film was produced at each temperature of 200 ° C. (Example 17), 400 ° C. (Example 18), 500 ° C. (Example 19), and 600 ° C. (Comparative Example 22).
- the film formation speed at each film formation temperature is different, the film formation time was adjusted in consideration of this, and a zinc oxide-based transparent conductive film having a film thickness of 1005 to 1012 nm was prepared.
- the characteristics of the obtained film were evaluated in the same manner as in Examples 1 to 3.
- the film forming conditions and the characteristics of the obtained film are shown in Table 1.
- the film composition of Ga / (Zn + Ga) was 0.31 atomic% and was almost the same as the target composition.
- the Ra value and haze ratio also increased, but the surface resistance also increased.
- the film of Comparative Example 21 has a sufficiently low surface resistance, but has a low haze ratio and a weak light confinement effect, and cannot be used as a surface transparent electrode of a highly efficient solar cell.
- the film formation rate at the time of production was very slow and the productivity was poor, and the obtained film also had a high haze ratio but a high surface resistance, so it could not be used as a surface transparent electrode of a solar cell.
- the films of Examples 17 to 19 are not only low in surface resistance but also have a sufficiently high haze ratio of 8% or more, and thus are useful as surface transparent electrodes for highly efficient solar cells.
- Example 20 to 26 In the following procedure, a transparent conductive film laminate having a large surface irregularity having a structure in which a zinc oxide-based transparent conductive film was formed on an indium oxide-based transparent conductive film containing tin was produced by a sputtering method.
- the composition of the target used for the production of the underlying indium oxide-based transparent conductive film was 9.29 atomic% in Sn / (In + Sn), and ICP emission spectroscopic analysis (manufactured by Seiko Instruments Inc., SPS4000). ) was quantitatively analyzed. The purity of the target is 99.999%, and the size is 6 inches ( ⁇ ) ⁇ 5 mm (thickness).
- the film was formed by the apparatus used for the zinc oxide-based transparent conductive film of Examples 1 to 19, and the type of cathode was the same.
- a Corning 7059 glass substrate having a thickness of 1.1 mm was attached to the surface facing the target.
- the average light transmittance of the Corning 7059 glass substrate itself in the visible light wavelength region is 92%.
- the distance between the sputtering target and the substrate was 50 mm. When the degree of vacuum in the chamber reaches 2 ⁇ 10 ⁇ 4 Pa or less, 6 vol.
- sputtering film formation is performed while the substrate is stationary immediately above the center of the target, and an indium oxide-based transparent conductive film having a thickness of 150 nm is formed on the substrate. did.
- the indium oxide-based transparent conductive film produced by this method is a crystal film, and the surface roughness Ra is 1.32 nm.
- Example 20 the zinc oxide-based transparent conductive film was formed in the same manner as in Example 1, in Example 21, the zinc oxide-based transparent conductive film was formed in the same manner as in Example 3, and in Example 22, the Example A zinc oxide-based transparent conductive film is formed in the same manner as in Example 4, a zinc oxide-based transparent conductive film is formed in Example 23 as in Example 6, and a zinc oxide-based transparent conductive film is formed in Example 24 as in Example 7.
- a transparent conductive film is formed.
- Example 25 a zinc oxide-based transparent conductive film is formed in the same manner as in Example 9.
- Example 26 a zinc oxide-based transparent conductive film is formed in the same manner as in Example 10.
- a conductive film laminate was obtained. These configurations are shown in Table 2. Characteristic evaluation of the produced transparent conductive film laminate was performed in the same manner as the zinc oxide-based transparent conductive film of Examples 1 to 3, and evaluation of pole figure by X-ray diffraction measurement (X'Pert Pro MPD manufactured by PANalytical) And the degree of inclination of the c-axis of the zinc oxide-based transparent conductive film with respect to the vertical direction of the substrate was evaluated. Table 2 shows the characteristic evaluation results of the transparent conductive film laminates of Examples 20 to 26.
- the film composition of the underlying indium oxide-based transparent conductive film is almost the same as the composition of the target, and the deposition rate of the zinc oxide-based transparent conductive film is almost the same as when no indium oxide-based thin film is inserted into the base. A high deposition rate was achieved.
- the obtained transparent conductive film laminate had a markedly lower surface resistance than when no indium oxide-based transparent conductive film was inserted into the base.
- the surface roughness Ra value and the haze ratio of the transparent conductive film laminates of Examples 20 to 26 tended to be slightly lower than when the indium oxide thin film was not inserted into the underlayer, the surface transparency of the solar cell was observed.
- When used as an electrode a sufficiently high value was shown.
- the c-axis of the zinc oxide-based transparent conductive film was tilted by 15 ° or less with respect to the vertical direction of the substrate. Such a film can be used for a surface transparent electrode of a solar cell having an excellent light confinement effect.
- Comparative Examples 23 to 26 In the same manner as in Examples 20 to 26, an indium oxide-based transparent conductive film was used as a base, and a zinc oxide-based transparent conductive film described below was formed thereon to produce a transparent conductive film laminate. That is, in Comparative Example 23, a zinc oxide-based transparent conductive film was formed in the same manner as Comparative Example 2, in Comparative Example 24, a zinc oxide-based transparent conductive film was formed in the same manner as Comparative Example 3, and Comparative Example 25 was a comparative example. In the same manner as in Example 8, a zinc oxide-based transparent conductive film was formed. In Comparative Example 26, a zinc oxide-based transparent conductive film was formed in the same manner as in Comparative Example 9 to obtain a transparent conductive film laminate.
- Table 2 shows the characteristics evaluation results of the transparent conductive film laminates of Comparative Examples 23 to 26.
- the transparent conductive film laminates of Comparative Examples 23 to 26 had a lower surface resistance than the case where the indium oxide-based transparent conductive film was not inserted into the base, but the surface roughness Ra value of the transparent conductive film laminate was The haze ratio tended to be equal to or less than that when no indium oxide thin film was inserted into the base.
- the transparent conductive film laminates of Comparative Examples 23 and 25 have a low surface resistance and are sufficient, but the haze ratio is low and the light confinement effect is weak, so that they cannot be used as a surface transparent electrode of a highly efficient solar cell.
- the transparent conductive film laminates of Comparative Examples 24 and 26 have high Ra values and haze ratios, but have extremely high surface resistance, and thus cannot be used as surface transparent electrodes for solar cells. Therefore, these films cannot be used for the surface transparent electrode of a highly efficient solar cell.
- Examples 27 to 33 The manufacturing conditions of the underlying indium oxide-based transparent conductive film shown in Examples 20 to 26 were changed to a method of annealing in vacuum after forming the substrate without heating, instead of heating. It was produced under the same conditions. As shown in Table 2, the annealing conditions were 300 to 400 ° C. and 30 to 60 minutes in a vacuum.
- the indium oxide-based transparent conductive film produced by this method is a crystalline film, and the surface roughness Ra is 1.3 to 2.1 nm.
- a zinc oxide-based transparent conductive film described below was formed on the indium oxide-based transparent conductive film.
- Example 27 the zinc oxide-based transparent conductive film of Example 1 is formed, in Example 28, the zinc oxide-based transparent conductive film of Example 3 is formed, and in Example 29, the zinc oxide-based transparent conductive film of Example 4 is formed. A conductive film is formed.
- Example 30 the zinc oxide-based transparent conductive film of Example 6 is formed.
- Example 31 the zinc oxide-based transparent conductive film of Example 7 is formed.
- Example 32 the zinc oxide-based transparent conductive film is formed.
- a zinc oxide-based transparent conductive film was formed, and in Example 33, the zinc oxide-based transparent conductive film of Example 10 was formed to obtain a transparent conductive film laminate.
- the characteristics evaluation of the produced transparent conductive film laminate was performed in the same manner as the zinc oxide-based transparent conductive films of Examples 1 to 3, and the pole figure was also evaluated by X-ray diffraction measurement.
- Table 2 shows the characteristic evaluation results of the transparent conductive film laminates of Examples 27 to 33.
- the film composition of the underlying indium oxide-based transparent conductive film is almost the same as the composition of the target, and the deposition rate of the zinc oxide-based transparent conductive film is almost the same as when no indium oxide-based thin film is inserted into the base. A high deposition rate was achieved.
- the transparent conductive film laminate had a significantly reduced surface resistance and an increased surface roughness Ra value and haze ratio as compared with the case where the indium oxide-based transparent conductive film was not inserted into the base.
- Example 20 and Example 27, Example 21 and Example 28, Example 22 and Example 29, Example 23 and Example 30, Example 24 and Example 31, Example 25 and Example 32 From the comparison between Example 26 and Example 33, it is more preferable to use an indium oxide-based transparent conductive film annealed after film formation without heating the substrate (Examples 27 to 33).
- Comparative Examples 27 to 30 A transparent conductive film laminate was produced in the same procedure as in Examples 27 to 33, and the configuration was as follows. That is, in Comparative Example 27, a zinc oxide-based transparent conductive film was formed in the same manner as in Comparative Example 2 on the indium oxide-based transparent conductive film formed under the conditions of Examples 27 to 28. The zinc oxide-based transparent conductive film of Comparative Example 3 was formed on the indium oxide-based transparent conductive film formed under the conditions of Examples 27 to 28. In Comparative Example 29, the oxide film formed under the conditions of Examples 29 to 30 was formed. The zinc oxide-based transparent conductive film of Comparative Example 5 was formed on the indium-based transparent conductive film.
- Comparative Example 30 Comparative Example 6 was formed on the indium oxide-based transparent conductive film formed under the conditions of Examples 27-28.
- a transparent conductive film laminate was obtained by forming a zinc oxide-based transparent conductive film.
- the characteristics evaluation of the produced transparent conductive film laminate was performed in the same manner as the zinc oxide-based transparent conductive films of Examples 1 to 3, and the pole figure was also evaluated by X-ray diffraction measurement.
- Table 2 shows the characteristic evaluation results of the transparent conductive film laminates of Comparative Examples 27 to 30.
- the transparent conductive film laminates of Comparative Examples 27 to 30 had lower surface resistance than the case where the indium oxide transparent conductive film was not inserted into the base.
- the transparent conductive film laminates of Comparative Examples 27 and 29 have a low surface resistance and are sufficient, but the haze ratio is low and the light confinement effect is weak, so that they cannot be used as the surface transparent electrode of a highly efficient solar cell.
- the transparent conductive film laminates of Comparative Examples 28 and 30 have high Ra values and haze ratios, but have extremely high surface resistance, and thus cannot be used as surface transparent electrodes for solar cells. Therefore, such a film cannot be used for a surface transparent electrode of a highly efficient solar cell.
- Examples 34 to 37, Comparative Example 31 A transparent conductive film laminate was produced by changing the composition of the indium oxide-based transparent conductive film used for the foundations of Examples 27 to 33.
- the target composition for producing the indium oxide-based transparent conductive film was changed so that Sn / (In + Sn) was in the range of 0.20 to 17.56 atomic%.
- the film formation conditions were as follows: the film formation gas pressure was 0.3 Pa, and the film formation gas was oxygen 8 vol. Using a mixed argon gas, the substrate was formed without heating, and then annealed in vacuum at 200 ° C. for 30 minutes.
- the composition of the base film obtained by this method was almost equivalent to the target composition as shown in Table 2.
- Example 31 As for the crystallinity of the film, when Sn / (In + Sn) was 17.56 atomic% (Comparative Example 31), it was a film in which crystalline and amorphous were mixed, but it was 0.20 to 14.95 atomic%. At that time (Examples 34 to 37), the film was a complete crystal film.
- the zinc oxide-based transparent conductive film of Example 17 was formed on the base film thus prepared. The film formation rate of the zinc oxide-based transparent conductive film was almost the same as when the indium oxide-based thin film was not inserted into the underlayer, and a high film formation rate could be realized. These configurations are shown in Table 2.
- the characteristics evaluation of the produced transparent conductive film laminate was performed in the same manner as the zinc oxide-based transparent conductive films of Examples 1 to 3, and the pole figure was also evaluated by X-ray diffraction measurement.
- Table 2 shows the evaluation results of the characteristics of the transparent conductive film laminate.
- the surface resistance was equal to or less than that in the case where the indium oxide-based transparent conductive film was not inserted in the base, and the conductive film showed sufficient conductivity.
- the surface roughness Ra value and the haze ratio of the laminate showed a tendency to increase by inserting a base film in Examples 34 to 37, but significantly decreased in Comparative Example 31.
- Comparative Example 31 The reason why the Ra value and the haze ratio decreased in Comparative Example 31 is that the base film was not completely a crystal film.
- Examples 34 to 37 show sufficiently high values when used as a surface transparent electrode of a solar cell, and can be used for a surface transparent electrode of a solar cell excellent in light confinement effect.
- Comparative Example 31 cannot be used because the haze ratio is small.
- Example 38 to 44 A transparent conductive film laminate was prepared by replacing the tin-containing indium oxide-based transparent conductive film used in the base films in Examples 20 to 26 with a titanium-containing indium oxide-based transparent conductive film.
- the underlying indium oxide-based transparent conductive film was produced under the following conditions. As shown in Table 3, the composition of the target used for producing the underlying indium oxide-based transparent conductive film was Ti / (In + Ti) of 1.73 atomic%, and ICP emission spectroscopic analysis (manufactured by Seiko Instruments Inc., SPS4000). ) was quantitatively analyzed. The purity of the target is 99.999%, and the size is 6 inches ( ⁇ ) ⁇ 5 mm (thickness).
- the film formation is performed by the apparatus used for the zinc oxide-based transparent conductive film of Examples 20 to 26, and the type of the cathode is the same.
- a Corning 7059 glass substrate having a thickness of 1.1 mm was attached to the surface facing the target.
- the average light transmittance of the Corning 7059 glass substrate itself in the visible light wavelength region is 92%.
- the distance between the sputtering target and the substrate was 50 mm. When the degree of vacuum in the chamber reaches 2 ⁇ 10 ⁇ 4 Pa or less, 6 vol.
- sputtering film formation is performed while the substrate is stationary immediately above the center of the target, and an indium oxide-based transparent conductive film having a thickness of 200 nm is formed on the substrate. did.
- the indium oxide-based transparent conductive film produced by this method is a crystal film, and the surface roughness Ra is 1.80 nm.
- a zinc oxide-based transparent conductive film described below was formed on the indium oxide-based transparent conductive film. That is, in Example 38, a zinc oxide-based transparent conductive film was formed as in Example 1, in Example 39, a zinc oxide-based transparent conductive film was formed as in Example 3, and in Example 40, Similarly, a zinc oxide-based transparent conductive film is formed. In Example 41, a zinc oxide-based transparent conductive film is formed as in Example 6. In Example 42, a zinc oxide-based transparent conductive film is formed as in Example 7. In Example 43, a zinc oxide-based transparent conductive film was formed in the same manner as in Example 9, and in Example 44, a zinc oxide-based transparent conductive film was formed in the same manner as in Example 10 to obtain a transparent conductive film laminate. .
- Table 3 shows the characteristics evaluation results of the transparent conductive film laminates of Examples 38 to 44.
- the film composition of the underlying indium oxide-based transparent conductive film is almost the same as the composition of the target, and the deposition rate of the zinc oxide-based transparent conductive film is almost the same as when no indium oxide-based thin film is inserted into the base. A high deposition rate was achieved.
- the surface resistance of the transparent conductive film laminate was significantly reduced as compared with the case where no indium oxide-based transparent conductive film was inserted into the base.
- the surface roughness Ra value and haze ratio of the transparent conductive film laminates of Examples 38 to 44 tended to be slightly lower than when the indium oxide thin film was not inserted into the underlayer, but the surface transparency of the solar cell was observed.
- a sufficiently high value was shown. Therefore, such a film
- Comparative Examples 32-35 Using the indium oxide-based transparent conductive film prepared in Examples 38 to 44 as a base, a zinc oxide-based transparent conductive film described below was formed thereon to prepare a transparent conductive film laminate. That is, in Comparative Example 32, a zinc oxide-based transparent conductive film was formed as in Comparative Example 2, in Comparative Example 33, a zinc oxide-based transparent conductive film was formed as in Comparative Example 3, and Comparative Example 34 was compared with Comparative Example 8. Similarly, a zinc oxide-based transparent conductive film was formed, and in Comparative Example 35, a zinc oxide-based transparent conductive film was formed in the same manner as in Comparative Example 9 to obtain a transparent conductive film laminate. These configurations are shown in Table 3.
- the characteristics evaluation of the produced transparent conductive film laminate was performed in the same manner as the zinc oxide-based transparent conductive films of Examples 1 to 3, and the pole figure was also evaluated by X-ray diffraction measurement.
- Table 3 shows the characteristic evaluation results of the transparent conductive film laminates of Comparative Examples 32-35.
- the transparent conductive film laminate had a lower surface resistance than the case where the indium oxide-based transparent conductive film was not inserted into the base, but the surface roughness Ra value and haze ratio of the transparent conductive film laminate were Compared to the case where no indium oxide thin film was inserted, the same or lower tendency was shown.
- the transparent conductive film laminates of Comparative Examples 32 and 34 have a low surface resistance and are sufficient, but have a low haze ratio and a weak light confinement effect, and cannot be used as a surface transparent electrode of a highly efficient solar cell.
- the transparent conductive film laminates of Comparative Examples 33 and 35 have a high Ra value and a high haze ratio, but cannot be used as a surface transparent electrode of a solar cell because the surface resistance is extremely high. Therefore, these films cannot be used for the surface transparent electrode of a highly efficient solar cell.
- Example 45 to 51 The manufacturing conditions of the indium oxide-based transparent conductive film used as the base in Examples 38 to 44 were changed to the method of annealing in vacuum after the substrate was formed without heating, instead of heating, and the rest was the same It was produced under the conditions. As shown in Table 3, the annealing conditions were 300 to 400 ° C. and 30 to 60 minutes in a vacuum.
- the indium oxide-based transparent conductive film produced by this method is a crystalline film, and the surface roughness Ra is 1.15 to 1.51 nm.
- a zinc oxide-based transparent conductive film described below was formed on the indium oxide-based transparent conductive film.
- Example 45 a zinc oxide-based transparent conductive film was formed as in Example 1, in Example 46, a zinc oxide-based transparent conductive film was formed as in Example 3, and in Example 47, Example 4 and Similarly, a zinc oxide-based transparent conductive film is formed, in Example 48, a zinc oxide-based transparent conductive film is formed as in Example 6, and in Example 49, a zinc oxide-based transparent conductive film is formed as in Example 7.
- Example 50 a zinc oxide-based transparent conductive film was formed in the same manner as in Example 9, and in Example 51, a zinc oxide-based transparent conductive film was formed in the same manner as in Example 10 to obtain a transparent conductive film laminate. .
- Table 2 These configurations are shown in Table 2.
- the characteristics evaluation of the produced transparent conductive film laminate was performed in the same manner as the zinc oxide-based transparent conductive films of Examples 1 to 3, and the pole figure was also evaluated by X-ray diffraction measurement.
- Table 3 shows the characteristic evaluation results of the transparent conductive film laminates of Examples 45 to 51.
- the film composition of the underlying indium oxide-based transparent conductive film is almost the same as the composition of the target, and the deposition rate of the zinc oxide-based transparent conductive film is almost the same as when no indium oxide-based thin film is inserted into the base. A high deposition rate was achieved.
- the transparent conductive film laminates of Examples 45 to 51 have a surface resistance Ra value significantly reduced as compared with the case where the indium oxide-based transparent conductive film is not inserted into the base. And the haze rate also increased.
- Example 38 and Example 45, Example 39 and Example 46, Example 40 and Example 47, Example 41 and Example 48, Example 42 and Example 49, Example 43 and Example 50 From the comparison between Example 44 and Example 51, it is better to use an indium oxide-based transparent conductive film annealed after forming the substrate without heating (Examples 45 to 51).
- Comparative Examples 36-39 A transparent conductive film laminate was produced in the same procedure as in Examples 45 to 51, and the configuration was as follows. That is, in Comparative Example 36, a zinc oxide-based transparent conductive film is formed on the indium oxide-based transparent conductive film in the same manner as in Comparative Example 2 as in Examples 45-51. In Comparative Example 37, in Examples 45-51. A zinc oxide-based transparent conductive film was formed on the indium oxide-based transparent conductive film formed under the conditions described above in the same manner as in Comparative Example 3. In Comparative Example 38, the indium oxide-based transparent conductive film of Examples 45 to 51 was formed.
- the zinc oxide-based transparent conductive film of Comparative Example 5 was formed, and in Comparative Example 39, the zinc oxide-based transparent conductive film was formed on the indium oxide-based transparent conductive film formed under the conditions of Examples 45 to 51 as in Comparative Example 6.
- a conductive film was formed to obtain a transparent conductive film laminate.
- the characteristics evaluation of the produced transparent conductive film laminate was performed in the same manner as the zinc oxide-based transparent conductive films of Examples 1 to 3, and the pole figure was also evaluated by X-ray diffraction measurement.
- Table 3 shows the characteristic evaluation results of the transparent conductive film laminates of Comparative Examples 36 to 39.
- the transparent conductive film laminate had a lower surface resistance than the case where an indium oxide-based transparent conductive film was not inserted into the base.
- the transparent conductive film laminates of Comparative Examples 36 and 38 have a low surface resistance and are sufficient, but have a low haze ratio and a weak light confinement effect, and cannot be used as a surface transparent electrode of a highly efficient solar cell.
- the transparent conductive film laminates of Comparative Examples 37 and 39 have a high Ra value and a high haze ratio, but cannot be used as a surface transparent electrode of a solar cell because of extremely high surface resistance. Therefore, such a film cannot be used for a surface transparent electrode of a highly efficient solar cell.
- Examples 52 to 55 Comparative Example 40
- a transparent conductive film laminate was produced by changing the composition of the indium oxide-based transparent conductive film used for the bases of Examples 45 to 51.
- the target composition for producing the indium oxide-based transparent conductive film was changed so that Ti / (In + Ti) was within the range of 0.35 to 7.25 atomic%.
- the film forming conditions were as follows: the film forming gas pressure was 0.3 Pa, and the film forming gas was oxygen at 7 vol. Using a mixed argon gas, the substrate was deposited without heating, and then annealed in vacuum at 300 ° C. for 30 minutes. The composition of the base film obtained by this method was almost the same as the target composition.
- Example 40 As for the crystallinity of the film, when Ti / (In + Ti) was 7.25 atomic% (Comparative Example 40), it was a film in which crystalline and amorphous were mixed, but 0.35 to 5.50 atomic%. At that time (Examples 52 to 55), the film was a complete crystal film.
- a zinc oxide-based transparent conductive film was formed in the same manner as in Example 14 on the thus-prepared base film having a thickness of 100 nm. The film formation rate of the zinc oxide-based transparent conductive film was almost the same as when the indium oxide-based thin film was not inserted into the underlayer, and a high film formation rate could be realized. These configurations are shown in Table 3.
- the characteristics evaluation of the produced transparent conductive film laminate was performed in the same manner as the zinc oxide-based transparent conductive films of Examples 1 to 3, and the pole figure was also evaluated by X-ray diffraction measurement.
- Table 3 shows the evaluation results of the characteristics of the transparent conductive film laminate.
- the surface resistance was equal to or less than that in the case where the indium oxide-based transparent conductive film was not inserted in the base, and the conductive film showed sufficient conductivity.
- the surface roughness Ra value and the haze ratio of the laminate showed a tendency to increase by inserting a base film in Examples 52 to 55, but significantly decreased in Comparative Example 40.
- the reason why the Ra value and the haze ratio decreased in Comparative Example 40 is that the base film was not completely a crystal film.
- the transparent conductive film laminates of Examples 52 to 55 have a sufficiently high value when used as a surface transparent electrode of a solar cell, and can be used for a surface transparent electrode of a solar cell excellent in light confinement effect. it can.
- Comparative Example 40 cannot be used because the haze ratio is small.
- Examples 56 to 59, Comparative Example 41 A tungsten-containing indium oxide-based transparent conductive film was used as a base film, and a zinc oxide-based transparent conductive film was formed thereon to produce a transparent conductive film laminate.
- the underlying indium oxide-based transparent conductive film was produced under the following conditions. As shown in Table 4, the target composition for producing the indium oxide-based transparent conductive film was changed so that W / (In + W) was within a range of 0.30 to 5.01 atomic%.
- the film forming conditions were as follows: the film forming gas pressure was 0.3 Pa, and the film forming gas was oxygen at 7 vol.
- Example 41 when W / (In + W) was 5.01 atomic% (Comparative Example 41), it was a film in which crystalline and amorphous were mixed, but 0.30 to 4.28 atomic%. At that time (Examples 56 to 59), the film was a complete crystal film.
- the zinc oxide-based transparent conductive film of Example 6 was formed on the base film having a thickness of 180 nm prepared as described above.
- the film formation rate of the zinc oxide-based transparent conductive film was almost the same as when the indium oxide-based thin film was not inserted into the underlayer, and a high film formation rate could be realized.
- These configurations are shown in Table 4.
- the characteristics evaluation of the produced transparent conductive film laminate was performed in the same manner as the zinc oxide-based transparent conductive films of Examples 1 to 3, and the pole figure was also evaluated by X-ray diffraction measurement.
- Table 4 shows the evaluation results of the characteristics of the transparent conductive film laminate. In any of the transparent conductive film laminates, the surface resistance was equal to or less than that in the case where the indium oxide-based transparent conductive film was not inserted in the base, and the conductive film showed sufficient conductivity.
- the surface roughness Ra value and the haze ratio of the laminated body tended to increase by inserting a base film in Examples 56 to 59, but significantly decreased in Comparative Example 41.
- the reason why the Ra value and the haze ratio decreased in Comparative Example 41 is that the base film was not completely a crystal film.
- the transparent conductive film laminates of Examples 56 to 59 have a sufficiently high value when used as a surface transparent electrode of a solar cell, and can be used for a surface transparent electrode of a solar cell excellent in light confinement effect. it can.
- the transparent conductive film laminate of Comparative Example 41 cannot be used because the haze ratio is small.
- Example 60 to 63 Comparative Example 42
- a zirconium-containing indium oxide-based transparent conductive film was used as a base film, and a zinc oxide-based transparent conductive film was formed thereon to produce a transparent conductive film laminate.
- the underlying indium oxide-based transparent conductive film was produced under the following conditions. As shown in Table 4, the target composition for producing the indium oxide-based transparent conductive film was changed so that Zr / (In + Zr) was in the range of 0.25 to 7.05 atomic%. As shown in Table 4, the film forming conditions were as follows: the film forming gas pressure was 0.2 Pa, and the film forming gas was oxygen at 6 vol.
- Example 42 when Zr / (In + Zr) was 7.05 atomic% (Comparative Example 42), the film was a mixture of crystalline and amorphous, but 0.25 to 6.50 atomic%. At that time (Examples 60 to 63), the film was a complete crystal film.
- a zinc oxide-based transparent conductive film was formed in the same manner as in Example 2 on the thus prepared base film having a thickness of 300 nm.
- the film formation rate of the zinc oxide-based transparent conductive film was almost the same as when the indium oxide-based thin film was not inserted into the underlayer, and a high film formation rate could be realized.
- These configurations are shown in Table 4.
- the characteristics evaluation of the produced transparent conductive film laminate was performed in the same manner as the zinc oxide-based transparent conductive films of Examples 1 to 3, and the pole figure was also evaluated by X-ray diffraction measurement.
- Table 4 shows the evaluation results of the characteristics of the transparent conductive film laminate. In any of the transparent conductive film laminates, the surface resistance was equal to or less than that in the case where the indium oxide-based transparent conductive film was not inserted in the base, and the conductive film showed sufficient conductivity.
- the surface roughness Ra value and the haze ratio of the laminated body tended to increase by inserting a base film in Examples 56 to 59, but significantly decreased in Comparative Example 42.
- the reason why the Ra value and the haze ratio decreased in Comparative Example 42 is that the base film was not completely a crystal film.
- the transparent conductive film laminates of Examples 60 to 63 have a sufficiently high value when used as a surface transparent electrode of a solar cell, and can be used for a surface transparent electrode of a solar cell excellent in light confinement effect. it can.
- the transparent conductive film laminate of Comparative Example 42 cannot be used because the haze ratio is small.
- Example 64 to 67 Comparative Example 43
- a zinc oxide-based transparent conductive film was formed thereon to produce a transparent conductive film laminate.
- the underlying indium oxide-based transparent conductive film was produced under the following conditions. As shown in Table 4, the target composition for producing the indium oxide-based transparent conductive film was changed so that Mo / (In + Mo) was in the range of 0.25 to 7.50 atomic%. As shown in Table 4, the film formation conditions were a film formation gas pressure of 0.3 Pa, and a film formation gas of 7 vol.
- Example 43 when Mo / (In + Mo) was 7.50 atomic% (Comparative Example 43), the film was a mixture of crystalline and amorphous, but 0.25 to 6.85 atomic%. At that time (Examples 64 to 67), the film was a complete crystal film.
- a zinc oxide-based transparent conductive film was formed in the same manner as in Example 11 on the thus-prepared base film having a thickness of 180 nm.
- the film formation rate of the zinc oxide-based transparent conductive film was almost the same as when the indium oxide-based thin film was not inserted into the underlayer, and a high film formation rate could be realized.
- These configurations are shown in Table 4.
- the characteristics evaluation of the produced transparent conductive film laminate was performed in the same manner as the zinc oxide-based transparent conductive films of Examples 1 to 3, and the pole figure was also evaluated by X-ray diffraction measurement.
- Table 4 shows the evaluation results of the characteristics of the transparent conductive film laminate. In any of the transparent conductive film laminates, the surface resistance was equal to or less than that in the case where the indium oxide-based transparent conductive film was not inserted in the base, and the conductive film showed sufficient conductivity.
- the surface roughness Ra value and the haze ratio of the laminated body tended to increase by inserting a base film in Examples 64-67, but significantly decreased in Comparative Example 43.
- the reason why the Ra value and the haze ratio decreased in Comparative Example 43 is that the underlying film was not completely a crystalline film.
- the transparent conductive film laminates of Examples 64-67 show a sufficiently high value when used as a surface transparent electrode of a solar cell, and can be used for a surface transparent electrode of a solar cell excellent in light confinement effect. it can.
- the transparent conductive film laminate of Comparative Example 43 cannot be used because the haze ratio is small.
- the silicon-based thin film solar cell of the present invention employs a transparent conductive film excellent in hydrogen reduction resistance and an optical confinement effect and a transparent conductive film laminate using the same, it has a high photoelectric conversion efficiency. It is a battery.
- a transparent conductive film having high conductivity and high transmittance in the visible light region includes liquid crystal display elements in addition to solar cells, electrodes of other various light receiving elements, and further, heat ray reflective films for automobile windows and buildings, It can also be used as various anti-fogging transparent heating elements such as antistatic films and frozen showcases.
Abstract
Description
そして、シリコン系薄膜太陽電池の種類もさらに多様化し、従来の光吸収層にアモルファスシリコンなどの非晶質薄膜を用いた非晶質薄膜太陽電池の他に、アモルファスシリコンに微細な結晶シリコンが混在した微結晶薄膜を用いた微結晶質薄膜太陽電池や結晶シリコンからなる結晶質薄膜を用いた結晶質薄膜太陽電池も開発され、これらを積層したハイブリッド薄膜太陽電池も実用化されている。
ここで光電変換ユニットまたは薄膜太陽電池は、それに含まれるp型とn型の導電型半導体層が非晶質か結晶質か微結晶にかかわらず、その主要部を占める光電変換層が非晶質のものは非晶質ユニットまたは非晶質薄膜太陽電池と称され、光電変換層が結晶質のものは結晶質ユニットまたは結晶質薄膜太陽電池と称され、光電変換層が微結晶質のものは微結晶質ユニットまたは微結晶質薄膜太陽電池と称されている。
この透明導電膜の凹凸の度合いを表す指標としてヘイズ率がある。これは特定の光源の光を透明導電膜が付いた透光性基板に入射した際に透過する光のうち、光路が曲げられた散乱成分を全成分で割ったものに相当し、通常可視光を含むC光源を用いて測定される。一般的には凹凸の高低差を大きくするほど、または凹凸の凸部と凸部の間隔が大きくなるほどヘイズ率が高くなり、光電変換ユニット内に入射された光は有効に閉じ込められ、いわゆる光閉じ込め効果が優れている。
上記目的から、凹凸の度合いが高くてヘイズ率の高い透明導電膜として、熱CVD法によって製造される酸化錫を主成分とした金属酸化物材料が知られており、薄膜太陽電池の透明電極として一般に利用されている。
酸化錫を主成分とする透明導電膜の水素による還元を防止する方法として、非特許文献1では、熱CVD法で形成した凹凸の度合いの高い酸化錫からなる透明導電膜の上に、還元耐性の優れた酸化亜鉛膜をスパッタリング法で薄く形成する方法が提案されている。酸化亜鉛は亜鉛と酸素との結合が強いため、耐水素還元性に優れているため、上記構造とすることにより、透明導電膜の透明性を高く保つことができることが開示されている。
しかしながら、上記構造の透明導電膜を得るためには2種類の手法を組合せて成膜しなければならないため、コスト高となり実用的ではない。また、酸化錫系透明導電膜と酸化亜鉛系透明導電膜の積層膜を全てスパッタリング法で製造する手法については、透明度の高い酸化錫系透明導電膜を、スパッタリング法で製造することができないなどの理由から実現不可能であるとされている。
また、非特許文献3では、酸化亜鉛を主成分として、従来のスパッタリング法で作製される、表面凹凸の小さな透明導電膜を得た後で、膜の表面を酸でエッチングして表面を凹凸化し、ヘイズ率の高い透明導電膜を製造する方法が開示されている。しかし、この方法では、乾式工程で、真空プロセスであるスパッタリング法で膜を製造した後に、大気中で酸エッチングを行って乾燥し、再び乾式工程のCVD法で半導体層を形成しなければならず、工程が複雑となり製造コストが高くなるなどの課題があった。
これを用いれば従来よりも低抵抗で高透過性の高品質な透明導電膜を成膜できるので、高変換効率の太陽電池の製造に適用できる。しかしながら、近年では、より高変換効率の太陽電池が求められており、それに用いることができる高品質な透明導電膜が必要とされている。
―[Al]+0.30≦[Ga] ≦―2.68×[Al]+1.74 ・・・(1)
(但し、[Al]は、Al/(Zn+Al)の原子数比(%)で表したアルミニウム含有量であり、一方、[Ga]は、Ga/(Zn+Ga)の原子数比(%)で表したガリウム含有量である。)
また、本発明の第3の発明によれば、第1の発明において、ヘイズ率が10%以上であることを特徴とする透明導電膜が提供される。
また、本発明の第4の発明によれば、第1の発明において、ヘイズ率が16%以上であることを特徴とする透明導電膜が提供される。
また、本発明の第5の発明によれば、第1~4のいずれかの発明において、表面抵抗が20Ω/□以下であることを特徴とする透明導電膜が提供される。
さらに、本発明の第6の発明によれば、第5の発明において、表面抵抗が15Ω/□以下であることを特徴とする透明導電膜が提供される。
さらに、本発明の第9の発明によれば、第8の発明において、透明導電膜(II)が、六方晶系の結晶相を含む結晶膜であることを特徴とする透明導電膜積層体が提供される。
また、本発明の第10の発明によれば、第9の発明において、六方晶系の結晶相が、略c軸配向性を有し、c軸傾斜角度が基板面の垂直方向に対して10°以下であることを特徴とする透明導電膜積層体が提供される。
また、本発明の第11の発明によれば、第8の発明において、酸化インジウム系透明導電膜(I)が、酸化インジウムを主成分とし、Sn、Ti、W、Mo、又はZrから選ばれる1種以上の金属元素を含有した結晶膜であることを特徴とする透明導電膜積層体が提供される。
また、本発明の第12の発明によれば、第8又は11の発明において、酸化インジウム系透明導電膜(I)が、酸化インジウムを主成分とし、かつSnを含有し、その含有割合がSn/(In+Sn)原子数比で15原子%以下であることを特徴とする透明導電膜積層体が提供される。
また、本発明の第13の発明によれば、第8又は11の発明において、酸化インジウム系透明導電膜(I)が、酸化インジウムを主成分とし、かつTiを含有し、その含有割合がTi/(In+Ti)原子数比で5.5原子%以下であることを特徴とする透明導電膜積層体が提供される。
また、本発明の第14の発明によれば、第8又は11の発明において、酸化インジウム系透明導電膜(I)が、酸化インジウムを主成分とし、かつWを含有し、その含有割合がW/(In+W)原子数比で4.3原子%以下であることを特徴とする透明導電膜積層体が提供される。
また、本発明の第15の発明によれば、第8又は11の発明において、酸化インジウム系透明導電膜(I)が、酸化インジウムを主成分とし、かつZrを含有し、その含有割合がZr/(In+Zr)原子数比で6.5原子%以下であることを特徴とする透明導電膜積層体が提供される。
また、本発明の第16の発明によれば、第8又は11の発明において、酸化インジウム系透明導電膜(1)が、酸化インジウムを主成分とし、かつMoを含有し、その含有割合がMo/(In+Mo)原子数比で6.7原子%以下であることを特徴とする透明導電膜積層体が提供される。
また、本発明の第17の発明によれば、第8~16のいずれかの発明において、表面抵抗が20Ω/□以下であることを特徴とする透明導電膜積層体が提供される。
さらに、本発明の第18の発明によれば、第8~17の発明において、ヘイズ率が12%以上であることを特徴とする透明導電膜積層体が提供される。
また、本発明の第20の発明によれば、第19の発明において、酸化インジウム系透明導電膜(I)が、基板温度100℃以下、スパッタリングガス圧0.1~1.0Paの条件で、非晶質膜として形成された後に、引き続き、200~400℃に加熱処理されて、結晶化されることを特徴とする透明導電膜積層体の製造方法が提供される。
さらに、本発明の第21の発明によれば、第19の発明において、酸化インジウム系透明導電膜(I)が、基板温度200~400℃、スパッタリングガス圧0.1~1.0Paの条件で、結晶膜として形成されることを特徴とする透明導電膜積層体の製造方法が提供される。
しかも、この透明導電膜は、スパッタリング法のみで製造することができるため、薄膜太陽電池の表面透明電極用として優れており、工業的に有用である。また、上記透明導電膜をより低抵抗の他の透明導電膜上に積層した透明導電膜積層体とすることにより、より低抵抗の、薄膜太陽電池の表面透明電極が得られ、該透明導電膜積層体は、従来の熱CVD法による透明導電膜と比べて安価に提供することができる。したがって、高効率のシリコン系薄膜太陽電池を簡単なプロセスで安価に提供することができるため工業的に極めて有用である。
2 表面透明電極層
3 非晶質光電変換ユニット
4 結晶質光電変換ユニット
5 裏面電極
本発明の透明導電膜は、酸化亜鉛を主成分とし、アルミニウム又はガリウムから選ばれる1種以上の添加金属元素を含み、その含有量が下記の式(1)で示される範囲内であり、かつ表面粗さ(Ra)が35.0nm以上、表面抵抗が65Ω/□以下であることを特徴とする。
―[Al]+0.30≦[Ga] ≦―2.68×[Al]+1.74 ・・・(1)
(但し、[Al]は、Al/(Zn+Al)の原子数比(%)で表したアルミニウム含有量であり、一方、[Ga]は、Ga/(Zn+Ga)の原子数比(%)で表したガリウム含有量である。)
透明導電膜中のアルミニウムとガリウムの含有量が、式(1)で規定される範囲より多くなると、該透明導電膜上に形成されるシリコン系薄膜にアルミニウムとガリウムが拡散しやすくなり、特性の優れたシリコン系薄膜太陽電池を実現できないなどの問題が生じる。また、生産性の面でも、該透明導電膜中のアルミニウムとガリウムの含有量が式(1)で規定される範囲より多くなると、表面凹凸が大きくてヘイズ率の高い透明導電膜をスパッタリング法で高速に製造することができなくなってしまう。一方、式(1)で規定される範囲よりも少なくなると、導電性が不十分であり、太陽電池の表面透明電極として利用することができない。
非特許文献2に従えば、Al添加量が多く、表面凹凸のある膜は低速でなければ形成できない。高速で成膜すると表面凹凸性が低下してしまう。表面凹凸の形状も、高速で行うと所望のようにはならない。これまで透明導電膜中のAl添加量を少なくすることは、抵抗値の上昇に繋がるため全く検討されておらず、成膜速度を増加させたときの膜の表面凹凸性やその形状なども調べられていなかった。本発明の透明導電膜表面凹凸は、非特許文献2の範囲で得られる形状とは大きく違うものとなる。
表面電極に用いる酸化亜鉛系透明導電膜は、表面抵抗が低いほど、表面電極部での電力損失が小さいため大きなセル面積でも、高効率の太陽電池を実現できるので好ましい。これは、酸化亜鉛系透明導電膜を結晶膜とすることで達成しうる。逆に表面電極の表面抵抗が高いと、太陽電池のセルが大きい場合には、表面電極での電力損失が無視できないレベルに大きくなるため、セル面積を小さくして、抵抗の低い金属配線で多くの小型セルを配線して面積を増加させる必要がある。表面電極が65Ω/□以下であれば、少なくとも5cm□の太陽電池セルを実現できるが、20Ω/□以下であれば少なくとも8cm□の太陽電池セル、さらに15Ω/□以下であれば少なくとも12cm□のセルが、表面電極での電力損失の影響を考慮することなく実現できる。
小さなセル面積の太陽電池は、金属配線によって接続する必要があり、セルの間隔が多くなるなどの要因で、セルを接続して作製した一つのモジュールの単位面積当たり発電量が小さくなるだけでなく、セルの面積当たりの製造コストが増加するなどの問題があるため好ましくない。
本発明の酸化亜鉛系透明導電膜は、耐水素還元性に優れ、表面凹凸を有し、高いヘイズ率と高い導電性を兼ね備えた透明導電膜であり、しかもスパッタリング法のみで製造することができるため、薄膜太陽電池の表面透明電極用の透明導電膜として優れている。
本発明の酸化亜鉛系透明導電膜の製造方法は、酸化亜鉛を主成分とし、アルミニウム又はガリウムから選ばれる1種以上の添加金属元素を含む酸化物焼結体ターゲットを用いて、スパッタリング法によって、基板上に酸化亜鉛系透明導電膜(II)を形成する透明導電膜の製造方法であって、スパッタリングガス圧が2.0~15.0Pa、基板温度が200~500℃の条件で、前記酸化物焼結体ターゲットへの直流投入電力密度を1.66W/cm2以上として、高速で成膜することを特徴とする。
―[Al]+0.30≦[Ga] ≦―2.68×[Al]+1.74 ・・・(1)
(但し、[Al]は、Al/(Zn+Al)の原子数比(%)で表したアルミニウム含有量であり、一方、[Ga]は、Ga/(Zn+Ga)の原子数比(%)で表したガリウム含有量である。)
ところが、アルミニウムとガリウムの含有量が式(1)の範囲内よりも多くなると(図3の斜線部領域より右上の範囲)、表面凹凸の大きな膜がスパッタリング法で高速に得ることができなくなり、また式(1)で規定される範囲よりも少なくなると(図3の斜線部領域より左下の範囲)、導電性が不十分な膜しか得られず、何れの場合も、太陽電池の表面透明電極として利用することができない。
酸化亜鉛に対して酸化アルミニウムや酸化ガリウムのような高融点物質の添加量が多くなると、成膜時の膜の結晶成長が遅くなるため、ターゲットへの投入電力を高めて、基板へのスパッタ粒子の供給量を増加させるが、このようにすると、結晶成長に起因した凹凸が大きくならない。アルミニウムとガリウムが上記の様な組成であれば、1.66W/cm2以上の高い投入電力による高速成膜でも、膜の結晶粒が大きくて、表面凹凸性の大きな膜を得ることができるのである。
この酸化物焼結体は、原料粉末として、酸化亜鉛粉末に、酸化ガリウム粉末と酸化アルミニウム粉末を添加・混合した後、引き続き、この原料粉末に水系媒体を配合して得られたスラリーを粉砕・混合処理し、次に得られた混合物を成形し、その後、成形体を焼成することで製造できる。詳細な製造方法については、前記特許文献3に記載されている。
なお、この酸化物焼結体には、亜鉛やアルミニウムやガリウムや酸素以外に、他の元素(例えば、インジウム、チタン、タングステン、モリブデン、イリジウム、ルテニウム、レニウム、セリウム、マグネシウム、珪素、フッ素など)が、本発明の目的を損なわない範囲で含まれていてもかまわない。
なお、本発明は、搬送成膜(通過型成膜)にも適用できる。ターゲット上を基板が通過しながら成膜する通過型成膜において、例えば同様の投入電力密度において成膜した3.5nm・m/min(搬送速度(m/min)で割ると、得られる膜厚(nm)が算出される)の高速搬送成膜においても表面凹凸性が優れて、ヘイズ率の高い酸化亜鉛系透明導電膜を得ることができる。なお、この場合の成膜速度は、本発明の目的を達成できれば特に制限されない。
また、本発明は、ターゲットが平板状のプレーナー型マグネトロン方式のスパッタリング成膜に適用できるし、円筒形のターゲットを用いたロータリー型マグネトロン方式のスパッタリング成膜にも適用できる。
スパッタリングガス圧が、2.0Pa未満であると、表面凹凸の大きい膜が得られにくく、Ra値が35.0nm以上の膜が得られなくなってしまう。一方、15.0Paを超えると成膜速度が遅くなってしまい好ましくない。例えば、静止対向成膜において、ターゲットへの直流投入電力密度が1.66W/cm2以上の高い電力を投入して40nm/min以上の成膜速度を得るためには、スパッタリングガス圧は15.0Pa以下でなければならない。
本発明の透明導電膜は、より低抵抗な、薄膜太陽電池の表面電極用に透明導電膜の積層体として用いることができる。本発明の透明導電膜積層体は、透光性基板上に形成された酸化インジウム系透明導電膜(I)の表面に、上記した酸化亜鉛系透明導電膜(II)が形成されている。
―[Al]+0.30≦[Ga] ≦―2.68×[Al]+1.74 ・・・(1)
(但し、[Al]は、Al/(Zn+Al)の原子数比(%)で表したアルミニウム含有量であり、一方、[Ga]は、Ga/(Zn+Ga)の原子数比(%)で表したガリウム含有量である。)
酸化亜鉛系透明導電膜中のアルミニウムとガリウムの含有量が、式(1)で規定される範囲より多くなると、その上に形成するシリコン系薄膜にアルミニウムとガリウムが拡散しやすくなり特性の優れたシリコン系薄膜太陽電池を実現できない。また生産性の面でも、膜中のアルミニウムとガリウムの含有量が式(1)で規定される範囲より多くなると、表面凹凸が大きくてヘイズ率の高い透明導電膜をスパッタリング法で高速に製造することができない。一方、式(1)で規定される範囲よりも少なくなると、導電性が不十分であり、太陽電池の表面透明電極として利用することができない。
但し、該透明導電膜の表面粗さ(Ra)が70nmを超えると、該透明導電膜上に形成するシリコン系薄膜の成長に影響を及ぼし、該透明導電膜とシリコン系薄膜との界面に隙間が生じて接触性が悪化し、太陽電池特性が悪化するので、好ましくない。
本発明の透明導電膜積層体の表面抵抗は、好ましくは20Ω/□以下、より好ましくは13Ω/□以下、さらに好ましくは10Ω/□以下、最も好ましくは8Ω/□以下である。そのような表面抵抗を実現することができるのは、上記特徴の酸化インジウム系透明導電膜を下地に挿入する構造となるためである。
上述のように表面電極に用いる酸化亜鉛系透明導電膜は、表面抵抗が低いほど、表面電極部での電力損失が小さいため大きなセル面積でも、高効率の太陽電池を実現できるので好ましい。逆に表面電極の表面抵抗が高いと、太陽電池のセルが大きい場合に、表面電極での電力損失が無視できないレベルに大きくなるため、セル面積を小さくして、抵抗の低い金属配線で多くの小型セルを配線して面積を増加させる必要がある。表面電極が65Ω/□以下であれば、少なくとも5cm□の太陽電池セルを実現できるが、20Ω/□以下であれば少なくとも8cm□の太陽電池セルが実現でき、さらに13Ω/□以下であれば少なくとも15cm□のセルが、10Ω/□以下であれば少なくとも17cm□のセルが、8Ω/□以下であれば少なくとも20cm□のセルが、表面電極での電力損失の影響を考慮することなく実現できる。小さなセル面積の太陽電池は、金属配線によって接続する必要があり、セルの間隔が多くなるなどの要因で、セルを接続して作製した一つのモジュールの単位面積当たり発電量が小さくなるだけでなく、セルの面積当たりの製造コストが増加するなどの問題があるため好ましくない。
これにより、表面粗さが大きく、上記のようなヘイズ率が高くて低抵抗の透明導電膜積層体を実現できる。従来の薄膜X線回折測定(θ―2θ)で、ZnO系のスパッタ膜の配向性を評価すると、c軸配向に起因する回折ピークのみが測定され、ほとんどがc軸配向性と判断されてきた。なぜなら、c軸が基板の垂直方向から若干傾いていても、従来の薄膜XRD測定では、c軸方向の格子面(例えば(002)面や(004)面)の面間隔に起因した回折しか観察されないからである。しかし、本出願人は、X線極点図形測定による追究から、膜のc軸は、必ずしも基板面の垂直方向に成長するのではなく、垂直方向に対して若干傾いていることを明らかにした。本発明のような透明導電膜積層体の場合、酸化亜鉛系透明導電膜(II)のc軸の基板面の垂直方向に対する傾斜角度が10°以下である優れた略c軸配向性を有しているとき、高いヘイズ率が実現することができる。そして、更に、本発明のような透明導電膜積層体の酸化亜鉛系透明導電膜(II)のc軸の傾き度合いは、下地の酸化インジウム系透明導電膜(I)の製造条件に大きく依存する。
第1の方法では、基板温度100℃以下、スパッタリングガス圧0.1~1.0Paの条件で、非晶質膜を形成した後に、引き続き、200~400℃に加熱処理して、非晶質膜を結晶化し酸化インジウム系透明導電膜とする。また、第2の方法では、基板温度200~400℃、スパッタリングガス圧0.1~1.0Paの条件で、酸化インジウム系透明導電膜を結晶膜として形成する。
本発明では、酸化インジウム系透明導電膜(I)の形成方法として、酸化亜鉛系透明導電膜(II)の場合と同様に、ターゲットが平板状のプレーナー型マグネトロン方式のスパッタリング成膜が適用できるし、円筒形のターゲットを用いたロータリー型マグネトロン方式のスパッタリング成膜も適用できる。
このような製造方法で得られた透明導電膜積層体は、高いヘイズ率と低い抵抗値を有するため、高効率の太陽電池の表面電極に有用である。
本発明の薄膜太陽電池は、透光性基板上に、上記の透明導電膜、あるいは、上記の透明導電膜積層体が形成され、前記透明導電膜上、あるいは、透明導電膜積層体上に、一導電型半導体層ユニット、光電変換層ユニット、又は他導電型半導体層ユニットから選ばれるユニットが少なくとも1種配置され、該ユニット上に裏面電極層が配置されている。
p型やn型の導電型半導体層は、光電変換ユニット内に内部電界を生じさせる役目を果たし、この内部電界の大きさによって薄膜太陽電池の重要な特性の1つである開放電圧(Voc)の値が左右される。i型層は実質的に真性の半導体層であって光電変換ユニットの厚さの大部分を占め、光電変換作用は主としてこのi型層内で生じる。このため、このi型層は通常i型光電変換層または単に光電変換層と呼ばれる。光電変換層は真性半導体層に限らず、ドープされた不純物(ドーパント)によって吸収される光の損失が問題にならない範囲で微量にp型またはn型にドープされた層であってもよい。
このような薄膜太陽電池の変換効率を向上させる方法として、2以上の光電変換ユニットを積層してタンデム型太陽電池にする方法がある。この方法においては、薄膜太陽電池の光入射側に大きなバンドギャップを有する光電変換層を含む前方ユニットを配置し、その後方に順に小さなバンドギャップを有する光電変換層を含む後方ユニットを配置することにより、入射光の広い波長範囲にわたって光電変換を可能にし、これによって太陽電池全体としての変換効率の向上が図られる。このタンデム型太陽電池の中でも、特に非晶質光電変換ユニットと、結晶質或いは微結晶質光電変換ユニットを積層したハイブリッド薄膜太陽電池の代表的な構造を図2に示す。ハイブリッド薄膜太陽電池では、例えば、i型非晶質シリコンが光電変換し得る光の波長域は長波長側では800nm程度までであるが、i型結晶質或いは微結晶質シリコンはそれより長い約1150nm程度の波長までの光を光電変換することができる。
また、本発明のシリコン系薄膜太陽電池は、上述の表面凹凸が大きくて高いヘイズ率と低抵抗の酸化亜鉛系透明導電膜、もしくは、上記透明導電膜積層体を有し、その上に、一導電型半導体層、光電変換層、他導電型半導体層が少なくとも1組配置され、その上に裏面電極層が配置されたシリコン系薄膜太陽電池である。
(2)また、得られた透明導電性薄膜の組成は、ICP発光分光分析(セイコーインスツルメンツ社製、SPS4000)で定量分析した。
(3)膜の結晶性、配向性は、CuKα線を利用したX線回折装置(マックサイエンス社製、M18XHF22)によるX線回折測定で調べた。
(4)また、各透明導電性薄膜の比抵抗を、抵抗率計ロレスタEP(ダイアインスツルメンツ社製MCP-T360型)による四探針法で測定した。
(5)さらに、基板を含めた全光線光透過率と平行線透過率、全光線反射率と平行光反射率を分光光度計(日立製作所社製、U-4000)で測定した。
(6)膜のヘイズ率は、JIS規格K7136に基づいてヘイズメーター(村上色彩技術研究所社製HM-150)で評価した。膜の表面粗さ(Ra)は、原子間力顕微鏡(デジタルインスツルメンツ社製、NS-III、D5000システム)を用いて5μm×5μmの領域を測定した。
アルミニウムを添加元素として含有した酸化亜鉛焼結体ターゲット(住友金属鉱山製)を用いて、次のようにして表面凹凸の大きい酸化亜鉛系透明導電膜を作製した。
用いたターゲットの組成は、ICP発光分光分析(セイコーインスツルメンツ社製、SPS4000)で定量分析し、表1に示すように、Al/(Zn+Al)で0.30~0.65原子%であった。何れのターゲットとも純度は99.999%であり、ターゲットの大きさは6インチ(Φ)×5mm(厚さ)である。
このスパッタリングターゲットを、直流マグネトロンスパッタリング装置(トッキ社製、SPF503K)の強磁性体ターゲット用カソード(ターゲット表面上から1cm離れた位置での水平磁場強度が、最大で約80kA/m(1kG))に取り付け、該スパッタリングターゲットの対向面に、厚み1.1mmのコーニング7059ガラス基板を取り付けた。なお、コーニング7059ガラス基板自体の可視光波長領域での平均光透過率は、92%である。スパッタリングターゲットと基板との距離を50mmとした。
次に、チャンバ内を真空引きし、その真空度が、2×10-4Pa以下に達した時点で、純度99.9999質量%のArガスをチャンバ内に導入して、ガス圧3.0Paとした。基板温度は400℃とし、直流投入電力400W(ターゲットへの投入電力密度=直流投入電力÷ターゲット表面積=400W÷181cm2=2.210W/cm2)を、ターゲットと基板の間に投入し、直流プラズマを発生させた。ターゲット表面のクリーニングのため10分間プリスパッタリングを行った後で、基板をターゲット中心の直上部に静止したまま、スパッタリング成膜を実施した。高い投入電力であるため、成膜速度は68~70nm/minと速かった。
得られた透明導電性薄膜の膜厚、組成、膜の結晶性、配向性、各透明導電性薄膜の比抵抗を前記の方法で測定した。さらに、基板を含めた全光線光透過率と平行線透過率、全光線反射率と平行光反射率、膜のヘイズ率を前記の方法で測定した。
表1に実施例1~3で得られた膜の特性を示す。得られた膜の組成はターゲットの組成とほぼ同じであった。また膜厚は830~850nmであった。成膜速度が68~70nm/minと速かったにも関わらず、原子間力顕微鏡で測定した表面粗さRa値は35.2から56.1nmと高い値を示し、ヘイズ率も8~12.5%と高かった。図4に実施例2の膜の表面SEM写真を示したが、膜は大きなグレインで構成され、表面凹凸性が大きいことがわかる。実施例1、実施例3の膜の表面も同様の組織であることが確認されている。また表面抵抗は43~63Ω/□であり、高い導電性を示した。よって、実施例1~3により、ヘイズ率が高くて導電性に優れた酸化亜鉛系透明導電膜が高速に得ることができることが確認された。
実施例1~3とターゲット組成を変えた以外は、同様にしてアルミニウムを含む酸化亜鉛焼結体ターゲットから酸化亜鉛系透明導電膜を作製した。ターゲットとしては、その組成Al/(Zn+Al)が1.59原子%(比較例1)、0.80原子%(比較例2)、0.20原子%(比較例3)であるものを用いた。ターゲット組成以外は、実施例1~3と全て同じ条件とした。
得られた膜の特性を表1に示した。得られた膜の組成はターゲットの組成とほぼ同じであった。成膜時のターゲットへの投入電力密度は、実施例1~3と同じ2.210W/cm2としたことから、いずれも66~70nm/minの速い成膜速度が得られている。しかし、比較例1、2の膜は、導電性は良好であったが、実施例1~3と異なりRa値も低くてヘイズ率が低い膜であった。よって、光閉じ込め効果が不十分であるため高効率の太陽電池の表面透明電極として利用することはできない。また、比較例3の膜は、Ra値とヘイズ率は高いが、表面抵抗が高すぎるため、太陽電池の電極として利用することができない。
ガリウムを添加元素として含有した酸化亜鉛焼結体ターゲットを用いて、表面凹凸の大きい酸化亜鉛系透明導電膜を作製した。ターゲット組成Ga/(Zn+Ga)が、1.74原子%(実施例4)、0.87原子%(実施例5)、0.30原子%(実施例6)の割合で、ガリウムを含む酸化亜鉛焼結体ターゲットを用いて、ガス圧を8.0Pa、基板温度を300℃とした以外は、実施例1~3と同様の条件で酸化亜鉛系透明導電膜を作製した。また、得られた膜の評価は実施例1~3と同様に実施した。
膜の作製条件と得られた膜の特性を表1に示した。得られた膜の組成は、ターゲットの組成とほぼ同じであった。実施例4~6の膜は、膜厚が780~800nmの膜が、約71nm/minの高速で成膜されたが、膜のRa値は、何れも48~56nmと大きくてヘイズ率も10.8~12.1%と高く、しかも表面抵抗は11~25Ω/□の範囲内で高い導電性を示した。よって、このような膜は、光閉じ込め効果に優れた太陽電池の表面透明電極用に利用することができる。
実施例4~6と同様にガリウムを含む酸化亜鉛焼結体ターゲットから酸化亜鉛系透明導電膜を作製したが、ターゲット組成Ga/(Zn+Ga)が3.48原子%(比較例4)、2.62原子%(比較例5)、0.20原子%(比較例6)であるターゲットを用いた。ターゲット組成以外は、実施例4~6と全て同じ条件で酸化亜鉛系透明導電膜を作製した。成膜時のターゲットへの投入電力密度も実施例1~3と同じ2.210W/cm2であることから、70~72nm/minの速い成膜速度が得られている。得られた膜の評価は実施例1~3と同様に実施した。
得られた膜の特性を表1に示した。膜組成は、ターゲット組成とほぼ同じであった。比較例4、5の膜は、導電性は良好であったが、実施例4~6と異なりRa値も低くてヘイズ率が低い膜であった。よって、光閉じ込め効果が不十分であるため高効率の太陽電池の表面透明電極として利用することはできない。また、比較例6の膜は、Ra値とヘイズ率は高いが、表面抵抗が高すぎるため、太陽電池の電極として利用することができない。
アルミニウムとガリウムを添加元素として含有した酸化亜鉛焼結体ターゲットを用いて表面凹凸の大きい酸化亜鉛系透明導電膜を作製した。表1のターゲット組成で示したアルミニウムとガリウムを含む酸化亜鉛焼結体ターゲットを用いて、ガス圧を5.0Pa、基板温度を350℃とした以外は、実施例1~3と同様の条件で酸化亜鉛系透明導電膜を作製した。また、得られた膜の評価は実施例1~3と同様に実施した。
膜の作製条件と得られた膜の特性を表1に示した。膜の組成はターゲット組成とほぼ同じであった。実施例7~10の膜は、膜厚が824~851nmの膜で、約69nm/minの高速で成膜されたが、膜のRa値は何れも38~50nmと大きくてヘイズ率も8.5~12.1%と高く、しかも表面抵抗は29~57Ω/□の範囲内で高い導電性を示した。よってこのような膜は、光閉じ込め効果に優れた太陽電池の表面透明電極用に利用することができる。
実施例7~10と同様にアルミニウムとガリウムを含む酸化亜鉛焼結体ターゲットから酸化亜鉛系透明導電膜を作製したが、表1に示すように本発明の組成範囲から逸脱した組成のターゲットを用いた。ターゲット組成以外は、実施例7~10と全て同じ条件で酸化亜鉛系透明導電膜を作製した。成膜時のターゲットへの投入電力密度も実施例7~10と同じ2.210W/cm2であることから、66~70nm/minの速い成膜速度が得られている。得られた膜の評価は実施例1~3と同様に実施した。
得られた膜の特性を表1に示した。膜の組成はターゲット組成とほとんど同じであった。比較例7、8の膜は、導電性は良好であったが、実施例7~10と異なりRa値も低くてヘイズ率が低い膜であった。よって、光閉じ込め効果が不十分であるため高効率の太陽電池の表面透明電極として利用することはできない。また、比較例9の膜は、Ra値とヘイズ率は高いが、表面抵抗が高すぎるため、太陽電池の電極として利用することができない。
実施例1~3と同様にアルミニウムを含む酸化亜鉛焼結体ターゲットから酸化亜鉛系透明導電膜を作製したが、ターゲット組成Al/(Zn+Al)が3.16原子%であるターゲットを用いた。この組成のターゲットは非特許文献2でも用いられている。成膜時のターゲットへの投入電力密度を0.442~2.210W/cm2の範囲内で変化させた。ターゲット組成と投入電力以外は、実施例1~3と全て同じ条件で成膜を行い、膜組成Al/(Zn+Al)が3.18原子%の酸化亜鉛系透明導電膜を作製した。得られた膜の特性評価も実施例1~3と同様に実施した。
成膜条件と得られた膜の特性を表1に示した。成膜時のターゲットへの投入電力密度が増加するに伴い、成膜速度は増加した。比較例10に示すようにターゲットへの投入電力が0.442W/cm2の低パワー投入時は、Ra値とヘイズ率が高くて導電性も満足する透明導電膜が得られ、非特許文献2と同じ結果が得られた。しかし、比較例10では投入電力密度が低いため、成膜速度が著しく遅くて、実用的ではない。比較例11~13は、さらに投入電力密度を増加させた例であるが、投入電力密度の増加に伴いヘイズ率は著しく減少し、1.105W/cm2(比較例11)において、ヘイズ率の高い膜が得られていない。
実施例4~6と同様にガリウムを含む酸化亜鉛焼結体ターゲットから酸化亜鉛系透明導電膜を作製した。ターゲット組成Ga/(Zn+Ga)が4.99原子%であるターゲットを用い、成膜ガス圧を8.3Pa、成膜時のターゲットへの投入電力密度を0.442~2.210W/cm2の範囲内で変化させ、それ以外は実施例4~6と同じ条件にて成膜を行った。膜組成Ga/(Zn+Ga)が5.03原子%の酸化亜鉛系透明導電膜が得られている。得られた膜の特性評価は実施例1~3と同様に実施した。
成膜条件と得られた膜の特性を表1に示した。成膜時のターゲットへの投入電力密度が増加するに伴い、成膜速度は増加し、膜のRa値とヘイズ率は減少する傾向を示した。しかし、何れの投入電力密度においても、太陽電池の表面透明電極として利用できる高いヘイズ率の膜は得られなかった。
実施例4~6と同様にガリウムを含む酸化亜鉛焼結体ターゲットから酸化亜鉛系透明導電膜を作製した。ターゲット組成Ga/(Zn+Ga)が1.31原子%であるターゲットを用い、成膜ガス圧を5.5Pa、ターゲットへの投入電力密度を2.760W/cm2とし、成膜時間を変化させて、膜厚830nm(比較例18)、1010nm(実施例11)、1350nm(実施例12)、1620nm(実施例13)の酸化亜鉛系透明導電膜を作製した。得られた膜の特性評価は実施例1~3と同様に実施した。
成膜条件と得られた膜の特性を表1に示した。膜組成はGa/(Zn+Ga)は、何れも、1.35原子%でありターゲット組成とほぼ同じであった。膜厚が増加するに伴い、表面抵抗は減少したが、Ra値とヘイズ率も増加した。比較例18の膜は、表面抵抗は低くて十分であるが、ヘイズ率が低くて光閉じ込め効果が弱く、高効率の太陽電池の表面透明電極としては利用できない。しかし、実施例11~13の膜は、表面抵抗が低いだけでなくヘイズ率も8%以上と十分に高いため、高効率の太陽電池の表面透明電極として利用できる。
実施例7~10と同様にアルミニウムとガリウムを含む酸化亜鉛焼結体ターゲットから酸化亜鉛系透明導電膜を作製した。ターゲット組成は、Ga/(Zn+Ga)が0.28原子%、Al/(Zn+Al)が0.28原子%であり、ターゲットへの投入電力密度は1.660W/cm2、基板温度は300℃とし、ガス圧は変化させて、1.0Pa(比較例19)、2.0Pa(実施例14)、10.5Pa(実施例15)、15.0Pa(実施例16)、20.0Pa(比較例20)の各ガス圧にて酸化亜鉛系透明導電膜を作製した。各ガス圧における成膜速度を考慮して成膜時間を調整し、膜厚が1340~1360nmでほぼ同じの酸化亜鉛系透明導電膜を作製した。得られた膜の特性評価は、実施例1~3と同様に実施した。
成膜条件と得られた膜の特性を表1に示した。膜組成はターゲット組成とほぼ同じであった。成膜時のガス圧が増加するに伴い、Ra値とヘイズ率は増加した。比較例19の膜は、ヘイズ率が低くて光閉じ込め効果が弱く、高効率の太陽電池の表面透明電極としては利用できない。比較例20は、作製時の成膜速度が非常に遅くて生産性が悪く、また、得られた膜はヘイズ率が高いが表面抵抗が高いことと、膜の基板への付着力が弱くて剥がれやすくデバイスの電極として利用することができない。しかし、実施例14~16の膜は、表面抵抗が低いだけでなく、ヘイズ率も8%以上と十分に高く、膜の付着力も高いため、高効率の太陽電池の表面透明電極として利用できる。
実施例4~6と同様にガリウムを含む酸化亜鉛焼結体ターゲットから酸化亜鉛系透明導電膜を作製した。ターゲット組成はGa/(Zn+Ga)が0.30原子%であり、ターゲットへの投入電力密度は2.760W/cm2とし、ガス圧は6.0Pa、基板温度は変化させて、150℃(比較例21)、200℃(実施例17)、400℃(実施例18)、500℃(実施例19)、600℃(比較例22)の各温度にて酸化亜鉛系透明導電膜を作製した。各成膜温度における成膜速度は異なるため、それを考慮して成膜時間を調整し、膜厚が1005~1012nmの膜厚の酸化亜鉛系透明導電膜を作製した。得られた膜の特性評価は実施例1~3と同様に実施した。
成膜条件と得られた膜の特性を表1に示した。膜組成はGa/(Zn+Ga)は、何れも、0.31原子%でありターゲット組成とほぼ同じであった。基板温度が増加するに伴い、Ra値とヘイズ率も増加したが、表面抵抗も増加した。比較例21の膜は、表面抵抗は低くて十分であるが、ヘイズ率が低くて光閉じ込め効果が弱く、高効率の太陽電池の表面透明電極としては利用できない。比較例22は、作製時の成膜速度が非常に遅くて生産性が悪く、また得られた膜もヘイズ率が高いが表面抵抗も高いため、太陽電池の表面透明電極として利用することができない。しかし、実施例17~19の膜は、表面抵抗が低いだけでなくヘイズ率も8%以上と十分に高いため、高効率の太陽電池の表面透明電極として有用である。
以下の手順で、スズを含有する酸化インジウム系透明導電膜の上に酸化亜鉛系透明導電膜を形成した構造の表面凹凸の大きな透明導電膜積層体をスパッタリング法で作製した。
下地の酸化インジウム系透明導電膜の作製に用いたターゲットの組成は、表2に示すように、Sn/(In+Sn)で9.29原子%であり、ICP発光分光分析(セイコーインスツルメンツ社製、SPS4000)で定量分析した。ターゲットの純度は99.999%であり、大きさは6インチ(Φ)×5mm(厚さ)である。成膜は、実施例1~19の酸化亜鉛系透明導電膜で用いた装置で行い、カソードの種類も同じである。ターゲットの対向面に、厚み1.1mmのコーニング7059ガラス基板を取り付けた。なお、コーニング7059ガラス基板自体の可視光波長領域での平均光透過率は、92%である。スパッタリングターゲットと基板との距離を50mmとした。
チャンバ内の真空度が、2×10-4Pa以下に達した時点で、6vol.%のO2ガスを混合したArガスをチャンバ内に導入して、ガス圧0.6Paとし、基板を300℃まで加熱してから、直流投入電力300W(ターゲットへの投入電力密度=直流投入電力÷ターゲット表面積=300W÷181cm2=1.660W/cm2)を、ターゲットと基板の間に投入し、直流プラズマを発生させた。ターゲット表面のクリーニングのため10分間プリスパッタを行った後で、基板をターゲット中心の直上部に静止したまま、スパッタリング成膜を実施し、膜厚150nmの酸化インジウム系透明導電膜を基板上に形成した。なお、この方法で作製した酸化インジウム系透明導電膜は、結晶膜であり、表面粗さRaは1.32nmである。
この酸化インジウム系透明導電膜の上に、次に述べる酸化亜鉛系透明導電膜を形成した。すなわち、実施例20では実施例1と同様にして酸化亜鉛系透明導電膜を形成し、実施例21では実施例3と同様にして酸化亜鉛系透明導電膜を形成し、実施例22では実施例4と同様にして酸化亜鉛系透明導電膜を形成し、実施例23では実施例6と同様にして酸化亜鉛系透明導電膜を形成し、実施例24では実施例7と同様にして酸化亜鉛系透明導電膜を形成し、実施例25では実施例9と同様にして酸化亜鉛系透明導電膜を形成し、実施例26では実施例10と同様にして酸化亜鉛系透明導電膜を形成し、透明導電膜積層体を得た。これらの構成を表2に示した。作製した透明導電膜積層体の特性評価は、実施例1~3の酸化亜鉛系透明導電膜と同様に行った他、X線回折測定(PANalytical社製 X‘Pert Pro MPD)による極点図形の評価も行い、酸化亜鉛系透明導電膜のc軸が、基板の垂直方向に対してどれ位傾いているか評価した。
実施例20~26の透明導電膜積層体の特性評価結果を表2に示した。何れにおいても、下地の酸化インジウム系透明導電膜の膜組成はターゲットの組成とほぼ同じであり、酸化亜鉛系透明導電膜の成膜速度は下地に酸化インジウム系薄膜を挿入しない時とほぼ同じで高速の成膜速度を実現することができた。得られた透明導電膜積層体は、下地に酸化インジウム系透明導電膜を挿入しない場合と比べて、表面抵抗が格段に低下していた。実施例20~26の透明導電膜積層体の表面粗さRa値とヘイズ率は、下地に酸化インジウム系薄膜を挿入しない時と比べて若干低下する傾向が見られたが、太陽電池の表面透明電極として利用する際には十分な高い値を示した。酸化亜鉛系透明導電膜のc軸は、基板の垂直方向に対して、15°以下傾いていた。
このような膜は、光閉じ込め効果に優れた太陽電池の表面透明電極用に利用することができる。
実施例20~26と同様にして酸化インジウム系透明導電膜を下地として、その上に次に述べる酸化亜鉛系透明導電膜を形成して透明導電膜積層体を作製した。すなわち、比較例23では比較例2と同様にして酸化亜鉛系透明導電膜を形成し、比較例24では比較例3と同様にして酸化亜鉛系透明導電膜を形成し、比較例25は比較例8と同様にして酸化亜鉛系透明導電膜を形成し、比較例26では比較例9と同様にして酸化亜鉛系透明導電膜を形成して、透明導電膜積層体を得た。これらの構成を表2に示した。作製した透明導電膜積層体の特性評価は、実施例1~3の酸化亜鉛系透明導電膜と同様に行った他、X線回折測定による極点図形の評価も実施した。
比較例23~26の透明導電膜積層体の特性評価結果を表2に示した。比較例23~26の透明導電膜積層体は、下地に酸化インジウム系透明導電膜を挿入しない場合と比べて、表面抵抗が低下していたが、透明導電膜積層体の表面粗さRa値とヘイズ率は、下地に酸化インジウム系薄膜を挿入しない時と比べて同等以下の傾向を示した。比較例23、25の透明導電膜積層体は、表面抵抗は低くて十分であるが、ヘイズ率が低くて光閉じ込め効果が弱く、高効率の太陽電池の表面透明電極としては利用できない。比較例24、26の透明導電膜積層体は、Ra値とヘイズ率は高いが表面抵抗が極めて高いため、太陽電池の表面透明電極として利用することができない。よってこれらの膜は、高効率の太陽電池の表面透明電極用に利用することができない。
実施例20~26に示した下地の酸化インジウム系透明導電膜の作製条件において、加熱成膜でなく、基板を非加熱で成膜してから真空中でアニールする方法に変更し、それ以外は同じ条件で作製した。アニールの条件は表2に示したように、真空中で300~400℃、30~60分とした。なお、この方法で作製した酸化インジウム系透明導電膜は、何れも結晶膜であり、表面粗さRaは1.3~2.1nmである。
この酸化インジウム系透明導電膜の上に、次に述べる酸化亜鉛系透明導電膜を形成した。すなわち、実施例27では実施例1の酸化亜鉛系透明導電膜を形成し、実施例28では実施例3の酸化亜鉛系透明導電膜を形成し、実施例29では実施例4の酸化亜鉛系透明導電膜を形成し、実施例30では実施例6の酸化亜鉛系透明導電膜を形成し、実施例31では実施例7の酸化亜鉛系透明導電膜を形成し、実施例32では実施例9の酸化亜鉛系透明導電膜を形成し、実施例33では実施例10の酸化亜鉛系透明導電膜を形成し、透明導電膜積層体を得た。これらの構成を表2に示した。作製した透明導電膜積層体の特性評価は、実施例1~3の酸化亜鉛系透明導電膜と同様に行った他、X線回折測定による極点図形の評価も実施した。
実施例27~33の透明導電膜積層体の特性評価結果を表2に示した。何れにおいても、下地の酸化インジウム系透明導電膜の膜組成はターゲットの組成とほぼ同じであり、酸化亜鉛系透明導電膜の成膜速度は下地に酸化インジウム系薄膜を挿入しない時とほぼ同じで高速の成膜速度を実現することができた。また、表2に示すように透明導電膜積層体は、下地に酸化インジウム系透明導電膜を挿入しない場合と比べて、表面抵抗が格段に低下し、表面粗さRa値とヘイズ率も増加した。
また、実施例20と実施例27、実施例21と実施例28、実施例22と実施例29、実施例23と実施例30、実施例24と実施例31、実施例25と実施例32、実施例26と実施例33の比較から、基板を非加熱とした成膜の後でアニール処理した酸化インジウム系透明導電膜を下地に使用した方が(実施例27~33)、加熱成膜による酸化インジウム系透明導電膜を下地に使用したとき(実施例20~26)と比べて、表面粗さRaとヘイズ率が大きな膜が得られることがわかる。
よって、このような透明度電膜積層体は、光閉じ込め効果に優れた太陽電池の表面透明電極用に利用することができる。
実施例27~33と同様の手順で透明導電膜積層体を作製したが、その構成を以下のようにした。すなわち、比較例27では、実施例27~28の条件で成膜した酸化インジウム系透明導電膜の上に比較例2と同様にして酸化亜鉛系透明導電膜を形成し、比較例28では、実施例27~28の条件で成膜した酸化インジウム系透明導電膜の上に比較例3の酸化亜鉛系透明導電膜を形成し、比較例29では、実施例29~30の条件で成膜した酸化インジウム系透明導電膜の上に比較例5の酸化亜鉛系透明導電膜を形成し、比較例30では、実施例27~28の条件で成膜した酸化インジウム系透明導電膜の上に比較例6の酸化亜鉛系透明導電膜を形成して、透明導電膜積層体を得た。作製した透明導電膜積層体の特性評価は、実施例1~3の酸化亜鉛系透明導電膜と同様に行った他、X線回折測定による極点図形の評価も実施した。
比較例27~30の透明導電膜積層体の特性評価結果を表2に示した。比較例27~30の透明導電膜積層体は、下地に酸化インジウム系透明導電膜を挿入しない場合と比べて、表面抵抗が低下していた。しかし、比較例27、29の透明導電膜積層体は、表面抵抗は低くて十分であるが、ヘイズ率が低くて光閉じ込め効果が弱く、高効率の太陽電池の表面透明電極としては利用できない。比較例28、30の透明導電膜積層体は、Ra値とヘイズ率は高いが表面抵抗が極めて高いため、太陽電池の表面透明電極として利用することができない。よってこのような膜は、高効率の太陽電池の表面透明電極用に利用することができない。
実施例27~33の下地に用いた酸化インジウム系透明導電膜の組成を変えて、透明導電膜積層体を作製した。表2に示すように、酸化インジウム系透明導電膜を作製する際のターゲット組成を、Sn/(In+Sn)が0.20~17.56原子%の範囲内で変化させた。成膜条件は、成膜ガス圧を0.3Pa、成膜ガスには酸素を8vol.%混合したアルゴンガスを用い、基板を非加熱で成膜した後で200℃にて30分間真空中でアニールした。この方法で得られた下地膜の組成は、何れも表2に示すようにターゲット組成とほぼ同等であった。膜の結晶性は、Sn/(In+Sn)が17.56原子%のとき(比較例31)は、結晶質と非晶質が混在した膜であったが、0.20~14.95原子%のとき(実施例34~37)は、完全な結晶膜であった。このように作製した下地膜の上に実施例17の酸化亜鉛系透明導電膜を形成した。酸化亜鉛系透明導電膜の成膜速度は下地に酸化インジウム系薄膜を挿入しない時とほぼ同じで高速の成膜速度を実現することができた。これらの構成を表2に示した。作製した透明導電膜積層体の特性評価は、実施例1~3の酸化亜鉛系透明導電膜と同様に行った他、X線回折測定による極点図形の評価も実施した。
透明導電膜積層体の特性評価結果を表2に示した。何れも透明導電膜積層体は、下地に酸化インジウム系透明導電膜を挿入しない場合と比べて、表面抵抗は同等以下であり十分な導電性を示した。しかし、積層体の表面粗さRa値とヘイズ率については、実施例34~37では下地膜を挿入することで増加する傾向が見られたが、比較例31では著しく減少した。比較例31でRa値とヘイズ率が減少した要因は下地膜が完全に結晶膜となっていなかったことによる。
実施例34~37では、太陽電池の表面透明電極として利用する際には十分な高い値を示し、光閉じ込め効果に優れた太陽電池の表面透明電極用に利用することができる。しかし、比較例31ではヘイズ率が小さいため利用できない。
実施例20~26における下地膜に用いたスズ含有の酸化インジウム系透明導電膜をチタン含有の酸化インジウム系透明導電膜に変えて透明導電膜積層体を作製した。下地の酸化インジウム系透明導電膜は以下の条件で作製した。
下地の酸化インジウム系透明導電膜の作製に用いたターゲットの組成は、表3に示すように、Ti/(In+Ti)で1.73原子%であり、ICP発光分光分析(セイコーインスツルメンツ社製、SPS4000)で定量分析した。ターゲットの純度は99.999%であり、大きさは6インチ(Φ)×5mm(厚さ)である。
成膜は、実施例20~26の酸化亜鉛系透明導電膜で用いた装置で行い、カソードの種類も同じである。ターゲットの対向面に、厚み1.1mmのコーニング7059ガラス基板を取り付けた。なお、コーニング7059ガラス基板自体の可視光波長領域での平均光透過率は、92%である。なお、スパッタリングターゲットと基板との距離を50mmとした。チャンバ内の真空度が、2×10-4Pa以下に達した時点で、6vol.%のO2ガスを混合したArガスをチャンバ内に導入して、ガス圧0.4Paとし、基板を300℃まで加熱してから、直流投入電力300W(ターゲットへの投入電力密度=直流投入電力÷ターゲット表面積=300W÷181cm2=1.660W/cm2)を、ターゲットと基板の間に投入し、直流プラズマを発生させた。ターゲット表面のクリーニングのため10分間プリスパッタを行った後で、基板をターゲット中心の直上部に静止したまま、スパッタリング成膜を実施し、膜厚200nmの酸化インジウム系透明導電膜を基板上に形成した。なお、この方法で作製した酸化インジウム系透明導電膜は、結晶膜であり、表面粗さRaは1.80nmである。
この酸化インジウム系透明導電膜の上に、次に述べる酸化亜鉛系透明導電膜を形成した。すなわち、実施例38では実施例1と同様に酸化亜鉛系透明導電膜を形成し、実施例39では実施例3と同様に酸化亜鉛系透明導電膜を形成し、実施例40では実施例4と同様に酸化亜鉛系透明導電膜を形成し、実施例41では実施例6と同様に酸化亜鉛系透明導電膜を形成し、実施例42では実施例7と同様に酸化亜鉛系透明導電膜を形成し、実施例43では実施例9と同様に酸化亜鉛系透明導電膜を形成し、実施例44では実施例10と同様に酸化亜鉛系透明導電膜を形成し、透明導電膜積層体を得た。これらの構成を表3に示した。作製した透明導電膜積層体の特性評価は、実施例1~3の酸化亜鉛系透明導電膜と同様に行った他、X線回折測定による極点図形の評価も実施した。
実施例38~44の透明導電膜積層体の特性評価結果を表3に示した。何れにおいても、下地の酸化インジウム系透明導電膜の膜組成はターゲットの組成とほぼ同じであり、酸化亜鉛系透明導電膜の成膜速度は下地に酸化インジウム系薄膜を挿入しない時とほぼ同じで高速の成膜速度を実現することができた。表3に示すように透明導電膜積層体は、下地に酸化インジウム系透明導電膜を挿入しない場合と比べて、表面抵抗が格段に低下していた。実施例38~44の透明導電膜積層体の表面粗さRa値とヘイズ率は、下地に酸化インジウム系薄膜を挿入しない時と比べて若干低下する傾向が見られたが、太陽電池の表面透明電極として利用する際には十分な高い値を示した。よってこのような膜は、光閉じ込め効果に優れた太陽電池の表面透明電極用に利用することができる。
実施例38~44で作製した酸化インジウム系透明導電膜を下地として、その上に次に述べる酸化亜鉛系透明導電膜を形成して透明導電膜積層体を作製した。すなわち、比較例32では比較例2と同様に酸化亜鉛系透明導電膜を形成し、比較例33では比較例3と同様に酸化亜鉛系透明導電膜を形成し、比較例34は比較例8と同様に酸化亜鉛系透明導電膜を形成し、比較例35では比較例9と同様に酸化亜鉛系透明導電膜を形成して、透明導電膜積層体を得た。これらの構成を表3に示した。作製した透明導電膜積層体の特性評価は、実施例1~3の酸化亜鉛系透明導電膜と同様に行った他、X線回折測定による極点図形の評価も実施した。
比較例32~35の透明導電膜積層体の特性評価結果を表3に示した。透明導電膜積層体は、下地に酸化インジウム系透明導電膜を挿入しない場合と比べて、表面抵抗が低下していたが、透明導電膜積層体の表面粗さRa値とヘイズ率は、下地に酸化インジウム系薄膜を挿入しない時と比べて同等以下の傾向を示した。比較例32、34の透明導電膜積層体は、表面抵抗は低くて十分であるが、ヘイズ率が低くて光閉じ込め効果が弱く、高効率の太陽電池の表面透明電極としては利用できない。比較例33、35の透明導電膜積層体は、Ra値とヘイズ率は高いが表面抵抗が極めて高いため、太陽電池の表面透明電極として利用することができない。よってこれらの膜は、高効率の太陽電池の表面透明電極用に利用することができない。
実施例38~44で下地とした酸化インジウム系透明導電膜の作製条件において、加熱成膜でなく、基板を非加熱で成膜してから真空中でアニールする方法に変更し、それ以外は同じ条件で作製した。アニールの条件は表3に示したとおり、真空中で300~400℃、30~60分とした。なお、この方法で作製した酸化インジウム系透明導電膜は、何れも結晶膜であり、表面粗さRaは1.15~1.51nmである。
この酸化インジウム系透明導電膜の上に、次に述べる酸化亜鉛系透明導電膜を形成した。すなわち、実施例45では実施例1と同様に酸化亜鉛系透明導電膜を形成し、実施例46では実施例3と同様に酸化亜鉛系透明導電膜を形成し、実施例47では実施例4と同様に酸化亜鉛系透明導電膜を形成し、実施例48では実施例6と同様に酸化亜鉛系透明導電膜を形成し、実施例49では実施例7と同様に酸化亜鉛系透明導電膜を形成し、実施例50では実施例9と同様に酸化亜鉛系透明導電膜を形成し、実施例51では実施例10と同様に酸化亜鉛系透明導電膜を形成し、透明導電膜積層体を得た。これらの構成を表2に示した。作製した透明導電膜積層体の特性評価は、実施例1~3の酸化亜鉛系透明導電膜と同様に行った他、X線回折測定による極点図形の評価も実施した。
実施例45~51の透明導電膜積層体の特性評価結果を表3に示した。何れにおいても、下地の酸化インジウム系透明導電膜の膜組成はターゲットの組成とほぼ同じであり、酸化亜鉛系透明導電膜の成膜速度は下地に酸化インジウム系薄膜を挿入しない時とほぼ同じで高速の成膜速度を実現することができた。また、表3に示すように実施例45~51の透明導電膜積層体は、下地に酸化インジウム系透明導電膜を挿入しない場合と比べて、表面抵抗が格段に低下し、表面粗さRa値とヘイズ率も増加した。
また、実施例38と実施例45、実施例39と実施例46、実施例40と実施例47、実施例41と実施例48、実施例42と実施例49、実施例43と実施例50、実施例44と実施例51の比較から、基板を非加熱で成膜した後でアニール処理した酸化インジウム系透明導電膜を下地に使用した方が(実施例45~51)、加熱成膜による酸化インジウム系透明導電膜を下地に使用したとき(実施例38~44)と比べて、表面粗さRaとヘイズ率が大きな膜が得られることがわかる。
よってこのような透明度電膜積層体は、光閉じ込め効果に優れた太陽電池の表面透明電極用に利用することができる。
実施例45~51と同様の手順で透明導電膜積層体を作製したが、その構成を以下のようにした。すなわち、比較例36では、実施例45~51と同様に酸化インジウム系透明導電膜の上に比較例2と同様に酸化亜鉛系透明導電膜を形成し、比較例37では、実施例45~51の条件で成膜した酸化インジウム系透明導電膜の上に比較例3と同様に酸化亜鉛系透明導電膜を形成し、比較例38では、実施例45~51の酸化インジウム系透明導電膜の上に比較例5の酸化亜鉛系透明導電膜を形成し、比較例39では、実施例45~51の条件で成膜した酸化インジウム系透明導電膜の上に比較例6と同様に酸化亜鉛系透明導電膜を形成して、透明導電膜積層体を得た。作製した透明導電膜積層体の特性評価は、実施例1~3の酸化亜鉛系透明導電膜と同様に行った他、X線回折測定による極点図形の評価も実施した。
比較例36~39の透明導電膜積層体の特性評価結果を表3に示した。透明導電膜積層体は、下地に酸化インジウム系透明導電膜を挿入しない場合と比べて、表面抵抗が低下していた。しかし、比較例36、38の透明導電膜積層体は、表面抵抗は低くて十分であるが、ヘイズ率が低くて光閉じ込め効果が弱く、高効率の太陽電池の表面透明電極としては利用できない。比較例37、39の透明導電膜積層体は、Ra値とヘイズ率は高いが表面抵抗が極めて高いため、太陽電池の表面透明電極として利用することができない。よってこのような膜は、高効率の太陽電池の表面透明電極用に利用することができない。
実施例45~51の下地に用いた酸化インジウム系透明導電膜の組成を変えて、透明導電膜積層体を作製した。表3に示すように、酸化インジウム系透明導電膜を作製する際のターゲット組成を、Ti/(In+Ti)が0.35~7.25原子%の範囲内で変化させた。成膜条件は、成膜ガス圧を0.3Pa、成膜ガスには酸素を7vol.%混合したアルゴンガスを用い、基板を非加熱で成膜した後で300℃にて30分間真空中でアニールした。この方法で得られた下地膜の組成は、何れもターゲット組成とほぼ同等であった。膜の結晶性は、Ti/(In+Ti)が7.25原子%のとき(比較例40)は、結晶質と非晶質が混在した膜であったが、0.35~5.50原子%のとき(実施例52~55)は、完全な結晶膜であった。このように作製した膜厚100nmの下地膜の上に実施例14と同様に酸化亜鉛系透明導電膜を形成した。酸化亜鉛系透明導電膜の成膜速度は下地に酸化インジウム系薄膜を挿入しない時とほぼ同じで高速の成膜速度を実現することができた。これらの構成を表3に示した。作製した透明導電膜積層体の特性評価は、実施例1~3の酸化亜鉛系透明導電膜と同様に行った他、X線回折測定による極点図形の評価も実施した。
透明導電膜積層体の特性評価結果を表3に示した。何れも透明導電膜積層体は、下地に酸化インジウム系透明導電膜を挿入しない場合と比べて、表面抵抗は同等以下であり十分な導電性を示した。しかし、積層体の表面粗さRa値とヘイズ率については、実施例52~55では下地膜を挿入することで増加する傾向が見られたが、比較例40では著しく減少した。比較例40でRa値とヘイズ率が減少した要因は下地膜が完全に結晶膜となっていなかったことによる。
実施例52~55の透明導電膜積層体は、太陽電池の表面透明電極として利用する際には十分な高い値を示し、光閉じ込め効果に優れた太陽電池の表面透明電極用に利用することができる。しかし、比較例40はヘイズ率が小さいため利用できない。
下地膜としてタングステン含有の酸化インジウム系透明導電膜を用い、その上に酸化亜鉛系透明導電膜を形成して透明導電膜積層体を作製した。下地の酸化インジウム系透明導電膜は以下の条件で作製した。
表4に示すように、酸化インジウム系透明導電膜を作製する際のターゲット組成を、W/(In+W)が0.30~5.01原子%の範囲内で変化させた。成膜条件は、成膜ガス圧を0.3Pa、成膜ガスには酸素を7vol.%混合したアルゴンガスを用い、直流電力400Wを投入して、基板を非加熱で成膜した後で300℃にて30分間真空中でアニールした。この方法で得られた下地膜の組成は、何れもターゲット組成とほぼ同等であった。膜の結晶性は、W/(In+W)が5.01原子%のとき(比較例41)は、結晶質と非晶質が混在した膜であったが、0.30~4.28原子%のとき(実施例56~59)は、完全な結晶膜であった。このように作製した膜厚180nmの下地膜の上に実施例6の酸化亜鉛系透明導電膜を形成した。酸化亜鉛系透明導電膜の成膜速度は下地に酸化インジウム系薄膜を挿入しない時とほぼ同じで高速の成膜速度を実現することができた。これらの構成を表4に示した。作製した透明導電膜積層体の特性評価は、実施例1~3の酸化亜鉛系透明導電膜と同様に行った他、X線回折測定による極点図形の評価も実施した。
透明導電膜積層体の特性評価結果を表4に示した。何れも透明導電膜積層体は、下地に酸化インジウム系透明導電膜を挿入しない場合と比べて、表面抵抗は同等以下であり十分な導電性を示した。しかし、積層体の表面粗さRa値とヘイズ率については、実施例56~59では下地膜を挿入することで増加する傾向が見られたが、比較例41では著しく減少した。比較例41でRa値とヘイズ率が減少した要因は下地膜が完全に結晶膜となっていなかったことによる。
実施例56~59の透明導電膜積層体は、太陽電池の表面透明電極として利用する際には十分な高い値を示し、光閉じ込め効果に優れた太陽電池の表面透明電極用に利用することができる。しかし、比較例41の透明導電膜積層体はヘイズ率が小さいため利用できない。
下地膜としてジルコニウム含有の酸化インジウム系透明導電膜を用い、その上に酸化亜鉛系透明導電膜を形成して透明導電膜積層体を作製した。下地の酸化インジウム系透明導電膜は以下の条件で作製した。
表4に示すように、酸化インジウム系透明導電膜を作製する際のターゲット組成を、Zr/(In+Zr)が0.25~7.05原子%の範囲内で変化させた。成膜条件は表4に示すように、成膜ガス圧を0.2Pa、成膜ガスには酸素を6vol.%混合したアルゴンガスを用い、直流電力400Wを投入して、基板を非加熱で成膜した後で400℃にて60分間真空中でアニールした。この方法で得られた下地膜の組成は、何れもターゲット組成とほぼ同等であった。膜の結晶性は、Zr/(In+Zr)が7.05原子%のとき(比較例42)は、結晶質と非晶質が混在した膜であったが、0.25~6.50原子%のとき(実施例60~63)は、完全な結晶膜であった。このように作製した膜厚300nmの下地膜の上に実施例2と同様に酸化亜鉛系透明導電膜を形成した。酸化亜鉛系透明導電膜の成膜速度は下地に酸化インジウム系薄膜を挿入しない時とほぼ同じで高速の成膜速度を実現することができた。これらの構成を表4に示した。作製した透明導電膜積層体の特性評価は、実施例1~3の酸化亜鉛系透明導電膜と同様に行った他、X線回折測定による極点図形の評価も実施した。
透明導電膜積層体の特性評価結果を表4に示した。何れも透明導電膜積層体は、下地に酸化インジウム系透明導電膜を挿入しない場合と比べて、表面抵抗は同等以下であり十分な導電性を示した。しかし、積層体の表面粗さRa値とヘイズ率については、実施例56~59では下地膜を挿入することで増加する傾向が見られたが、比較例42では著しく減少した。比較例42でRa値とヘイズ率が減少した要因は下地膜が完全に結晶膜となっていなかったことによる。
実施例60~63の透明導電膜積層体は、太陽電池の表面透明電極として利用する際には十分な高い値を示し、光閉じ込め効果に優れた太陽電池の表面透明電極用に利用することができる。しかし、比較例42の透明導電膜積層体はヘイズ率が小さいため利用できない。
下地膜としてモリブデン含有の酸化インジウム系透明導電膜を用い、その上に酸化亜鉛系透明導電膜を形成して透明導電膜積層体を作製した。下地の酸化インジウム系透明導電膜は以下の条件で作製した。
表4に示すように、酸化インジウム系透明導電膜を作製する際のターゲット組成を、Mo/(In+Mo)が0.25~7.50原子%の範囲内で変化させた。成膜条件は表4に示すように、成膜ガス圧を0.3Pa、成膜ガスには酸素を7vol.%混合したアルゴンガスを用い、直流電力400Wを投入して、基板を非加熱で成膜した後で300℃にて30分間真空中でアニールした。この方法で得られた下地膜の組成は、何れもターゲット組成とほぼ同等であった。膜の結晶性は、Mo/(In+Mo)が7.50原子%のとき(比較例43)は、結晶質と非晶質が混在した膜であったが、0.25~6.85原子%のとき(実施例64~67)は、完全な結晶膜であった。このように作製した膜厚180nmの下地膜の上に実施例11と同様に酸化亜鉛系透明導電膜を形成した。酸化亜鉛系透明導電膜の成膜速度は下地に酸化インジウム系薄膜を挿入しない時とほぼ同じで高速の成膜速度を実現することができた。これらの構成を表4に示した。作製した透明導電膜積層体の特性評価は、実施例1~3の酸化亜鉛系透明導電膜と同様に行った他、X線回折測定による極点図形の評価も実施した。
透明導電膜積層体の特性評価結果を表4に示した。何れも透明導電膜積層体は、下地に酸化インジウム系透明導電膜を挿入しない場合と比べて、表面抵抗は同等以下であり十分な導電性を示した。しかし、積層体の表面粗さRa値とヘイズ率については、実施例64~67では下地膜を挿入することで増加する傾向が見られたが、比較例43では著しく減少した。比較例43でRa値とヘイズ率が減少した要因は下地膜が完全に結晶膜となっていなかったことによる。
実施例64~67の透明導電膜積層体は、太陽電池の表面透明電極として利用する際には十分な高い値を示し、光閉じ込め効果に優れた太陽電池の表面透明電極用に利用することができる。しかし、比較例43の透明導電膜積層体はヘイズ率が小さいため利用できない。
Claims (22)
- 酸化亜鉛を主成分とし、アルミニウム又はガリウムから選ばれる1種以上の添加金属元素を含み、その含有量が下記の式(1)で示される範囲内であり、かつ表面粗さ(Ra)が35.0nm以上、表面抵抗が65Ω/□以下であることを特徴とする透明導電膜。
―[Al]+0.30≦[Ga] ≦―2.68×[Al]+1.74 ・・・(1)
(但し、[Al]は、Al/(Zn+Al)の原子数比(%)で表したアルミニウム含有量であり、一方、[Ga]は、Ga/(Zn+Ga)の原子数比(%)で表したガリウム含有量である。) - ヘイズ率が8%以上であることを特徴とする請求項1に記載の透明導電膜。
- ヘイズ率が10%以上であることを特徴とする請求項1又は2に記載の透明導電膜。
- ヘイズ率が16%以上であることを特徴とする請求項1~3のいずれかに記載の透明導電膜。
- 表面抵抗が20Ω/□以下であることを特徴とする請求項1に記載の透明導電膜。
- 表面抵抗が15Ω/□以下であることを特徴とする請求項1又は5に記載の透明導電膜。
- 酸化亜鉛を主成分とし、アルミニウム又はガリウムから選ばれる1種以上の添加金属元素を含む酸化物焼結体ターゲットを用いて、スパッタリング法によって、基板上に酸化亜鉛系透明導電膜(II)を形成する透明導電膜の製造方法であって、
スパッタリングガス圧が2.0~15.0Pa、基板温度が200~500℃の条件で、前記酸化物焼結体ターゲットへの直流投入電力密度を1.66W/cm2以上として、高速で成膜することを特徴とする請求項1~6のいずれかに記載の透明導電膜の製造方法。 - 基板上に形成された酸化インジウム系透明導電膜(I)上に、請求項1~6のいずれかに記載の酸化亜鉛系透明導電膜(II)が形成されたことを特徴とする透明導電膜積層体。
- 透明導電膜(II)が、六方晶系の結晶相を含む結晶膜であることを特徴とする請求項8に記載の透明導電膜積層体。
- 六方晶系の結晶相が、略c軸配向性を有し、c軸傾斜角度が基板面の垂直方向に対して10°以下であることを特徴とする請求項9に記載の透明導電膜積層体。
- 酸化インジウム系透明導電膜(I)が、酸化インジウムを主成分とし、Sn、Ti、W、Mo、又はZrから選ばれる1種以上の金属元素を含有した結晶膜であることを特徴とする請求項8に記載の透明導電膜積層体。
- 酸化インジウム系透明導電膜(I)が、酸化インジウムを主成分とし、かつSnを含有し、その含有割合がSn/(In+Sn)原子数比で15原子%以下であることを特徴とする請求項8又は11に記載の透明導電膜積層体。
- 酸化インジウム系透明導電膜(I)が、酸化インジウムを主成分とし、かつTiを含有し、その含有割合がTi/(In+Ti)原子数比で5.5原子%以下であることを特徴とする請求項8又は11に記載の透明導電膜積層体。
- 酸化インジウム系透明導電膜(I)が、酸化インジウムを主成分とし、かつWを含有し、その含有割合がW/(In+W)原子数比で4.3原子%以下であることを特徴とする請求項8又は11に記載の透明導電膜積層体。
- 酸化インジウム系透明導電膜(I)が、酸化インジウムを主成分とし、かつZrを含有し、その含有割合がZr/(In+Zr)原子数比で6.5原子%以下であることを特徴とする請求項8又は11に記載の透明導電膜積層体。
- 酸化インジウム系透明導電膜(1)が、酸化インジウムを主成分とし、かつMoを含有し、その含有割合がMo/(In+Mo)原子数比で6.7原子%以下であることを特徴とする請求項8又は11に記載の透明導電膜積層体。
- 表面抵抗が20Ω/□以下であることを特徴とする請求項8~16のいずれかに記載の透明導電膜積層体。
- ヘイズ率が12%以上であることを特徴とする請求項8~17のいずれかに記載の透明導電膜積層体。
- 先ず、Sn、Ti、W、Mo、又はZrから選ばれる1種以上の金属元素を含む酸化インジウムを主成分とする酸化物焼結体ターゲットを用いて、スパッタリング法で、酸化インジウム系透明導電膜(I)の結晶膜を基板上に形成し、次に、酸化亜鉛を主成分とし、アルミニウム又はガリウムから選ばれる1種以上の添加金属元素を含む酸化物焼結体ターゲットに切り替えて、酸化亜鉛系透明導電膜(II)を酸化インジウム系透明導電膜(I)の上に成膜することを特徴とする請求項8~18のいずれかに記載の透明導電膜積層体の製造方法。
- 酸化インジウム系透明導電膜(I)が、基板温度100℃以下、スパッタリングガス圧0.1~1.0Paの条件で、非晶質膜として形成された後に、引き続き、200~400℃に加熱処理されて、結晶化されることを特徴とする請求項19に記載の透明導電膜積層体の製造方法。
- 酸化インジウム系透明導電膜(I)が、基板温度200~400℃、スパッタリングガス圧0.1~1.0Paの条件で、結晶膜として形成されることを特徴とする請求項19に記載の透明導電膜積層体の製造方法。
- 透光性基板上に、請求項1~6に記載の透明導電膜、あるいは、請求項8~17に記載の透明導電膜積層体が形成され、前記透明導電膜上、あるいは、透明導電膜積層体上に、一導電型半導体層ユニット、光電変換層ユニット、又は他導電型半導体層ユニットから選ばれるユニットが少なくとも1種配置され、該ユニット上に裏面電極層が配置されたシリコン系薄膜太陽電池。
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CN201080011190.7A CN102348827B (zh) | 2009-03-13 | 2010-03-10 | 透明导电膜和透明导电膜层叠体及其制造方法、以及硅系薄膜太阳能电池 |
US13/255,749 US20120024381A1 (en) | 2009-03-13 | 2010-03-10 | Transparent conductive film and transparent conductive film laminated body and production method of same, and silicon-based thin film solar cell |
EP10750864.0A EP2407575B1 (en) | 2009-03-13 | 2010-03-10 | Transparent conductive film and transparent conductive film laminate, processes for production of same, and silicon thin film solar cell |
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WO2012053569A1 (ja) * | 2010-10-20 | 2012-04-26 | 住友金属鉱山株式会社 | 表面電極付透明導電基板の製造方法及び薄膜太陽電池の製造方法 |
JP2012089682A (ja) * | 2010-10-20 | 2012-05-10 | Sumitomo Metal Mining Co Ltd | 表面電極付透明導電基板の製造方法及び薄膜太陽電池の製造方法 |
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JP2014031565A (ja) * | 2012-08-06 | 2014-02-20 | Kochi Univ Of Technology | 酸化亜鉛を主成分とする膜構造体及びその製造方法、並びに該膜構造体からなる感受素子 |
WO2014061612A1 (ja) * | 2012-10-17 | 2014-04-24 | 旭硝子株式会社 | 導電性薄膜付きガラス基板、薄膜太陽電池、低放射ガラス基板、導電性薄膜付きガラス基板の製造方法 |
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WO2014073329A1 (ja) * | 2012-11-07 | 2014-05-15 | 住友金属鉱山株式会社 | 透明導電膜積層体及びその製造方法、並びに薄膜太陽電池及びその製造方法 |
JP2014095099A (ja) * | 2012-11-07 | 2014-05-22 | Sumitomo Metal Mining Co Ltd | 透明導電膜積層体及びその製造方法、並びに薄膜太陽電池及びその製造方法 |
JP2014095098A (ja) * | 2012-11-07 | 2014-05-22 | Sumitomo Metal Mining Co Ltd | 透明導電膜積層体及びその製造方法、並びに薄膜太陽電池及びその製造方法 |
JP2020033594A (ja) * | 2018-08-29 | 2020-03-05 | 国立研究開発法人産業技術総合研究所 | マグネトロンスパッタリング装置および金属酸化物膜の製造方法 |
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TWI493728B (zh) | 2015-07-21 |
EP2407575A4 (en) | 2012-09-05 |
JPWO2010104111A1 (ja) | 2012-09-13 |
TW201041153A (en) | 2010-11-16 |
EP2407575B1 (en) | 2015-08-12 |
TW201541654A (zh) | 2015-11-01 |
KR20110127182A (ko) | 2011-11-24 |
JP5621764B2 (ja) | 2014-11-12 |
US20120024381A1 (en) | 2012-02-02 |
CN102348827B (zh) | 2015-04-29 |
TWI584484B (zh) | 2017-05-21 |
CN102348827A (zh) | 2012-02-08 |
EP2407575A1 (en) | 2012-01-18 |
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