WO2023089654A1 - 半導体光電極の製造方法 - Google Patents

半導体光電極の製造方法 Download PDF

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Publication number
WO2023089654A1
WO2023089654A1 PCT/JP2021/042024 JP2021042024W WO2023089654A1 WO 2023089654 A1 WO2023089654 A1 WO 2023089654A1 JP 2021042024 W JP2021042024 W JP 2021042024W WO 2023089654 A1 WO2023089654 A1 WO 2023089654A1
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WO
WIPO (PCT)
Prior art keywords
thin film
semiconductor
semiconductor thin
photoelectrode
oxidation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
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PCT/JP2021/042024
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English (en)
French (fr)
Japanese (ja)
Inventor
裕也 渦巻
紗弓 里
晃洋 鴻野
武志 小松
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NTT Inc
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Nippon Telegraph and Telephone Corp
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Publication date
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Priority to PCT/JP2021/042024 priority Critical patent/WO2023089654A1/ja
Priority to JP2023561948A priority patent/JP7787436B2/ja
Publication of WO2023089654A1 publication Critical patent/WO2023089654A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
    • C25B11/075—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound
    • 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
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis

Definitions

  • the present invention relates to a method for manufacturing a semiconductor photoelectrode.
  • a device that generates hydrogen by a water splitting reaction using a semiconductor photoelectrode has an oxidation tank and a reduction tank that are connected via a proton exchange membrane. and a reduction electrode.
  • the oxidation electrode and the reduction electrode are electrically connected by a conducting wire.
  • the water splitting reaction using a photocatalyst consists of a water oxidation reaction and a proton reduction reaction.
  • an n-type photocatalyst material is irradiated with light, electrons and holes are generated and separated in the photocatalyst.
  • the holes move to the surface of the photocatalytic material and contribute to the water oxidation reaction.
  • the electrons move to the reduction electrode and contribute to the proton reduction reaction.
  • such oxidation-reduction reactions proceed and water-splitting reactions occur.
  • the oxide electrode is a semiconductor thin film, such as a gallium nitride (GaN) thin film grown on a sapphire substrate, gallium nitride, gallium nitride, and aluminum gallium nitride (AlGaN), or gallium nitride and indium gallium nitride (InGaN) on a sapphire substrate.
  • GaN gallium nitride
  • AlGaN aluminum gallium nitride
  • InGaN indium gallium nitride
  • a NiO layer for example, is formed as a catalyst material on the semiconductor surface for the purpose of promoting the oxygen generation reaction and suppressing the etching reaction.
  • NiO is formed by undergoing an oxidation process by heat treatment.
  • the present invention has been made in view of the above, and aims to improve the light energy conversion efficiency and life of a semiconductor photoelectrode.
  • a method for manufacturing a semiconductor photoelectrode according to one aspect of the present invention includes the steps of forming a semiconductor thin film on an insulating or conductive substrate; forming a metal layer on the surface of the semiconductor thin film; and oxidizing the layer to form a catalyst layer.
  • the light energy conversion efficiency and life of the semiconductor photoelectrode can be improved.
  • FIG. 1 is a cross-sectional view showing an example of the configuration of the semiconductor photoelectrode of this embodiment.
  • FIG. 2 is a cross-sectional view showing an example of the configuration of the semiconductor photoelectrode of this embodiment.
  • FIG. 3 is a flow chart showing an example of a method for manufacturing the semiconductor photoelectrode of FIG.
  • FIG. 4 is a flow chart showing an example of a method for manufacturing the semiconductor photoelectrode of FIG.
  • FIG. 5 is a diagram showing an outline of an apparatus for conducting an oxidation-reduction reaction test.
  • FIG. 1 is a cross-sectional view showing an example of the configuration of the semiconductor photoelectrode of this embodiment.
  • the semiconductor photoelectrode shown in FIG. 1 comprises an insulating or conductive substrate 11 , a semiconductor thin film 12 arranged on the substrate 11 , and a catalyst layer 13 arranged on the semiconductor thin film 12 .
  • the catalyst layer 13 is formed by oxidizing the metal layer by ozone oxidation, thereby improving the adhesion of the interface with the semiconductor thin film 12 .
  • an insulating or conductive substrate such as a sapphire substrate, GaN substrate, glass substrate, or Si substrate is used.
  • Gallium nitride, aluminum gallium nitride, or indium gallium nitride is used for the semiconductor thin film 12 .
  • the semiconductor thin film 12 may include metal oxides such as titanium oxide (TiO 2 ) and tungsten oxide (WO 3 ) having photocatalytic functions, or compound semiconductors such as tantalum nitride (Ta 3 N 5 ) and cadmium sulfide (CdS). may be used.
  • the catalyst layer 13 an oxide made of one or more metals selected from Ni, Co, Cu, W, Ta, Pd, Ru, Fe, Zn, and Nb is used.
  • the film thickness of the catalyst layer 13 is desirably 1 nm to 10 nm, particularly 1 nm to 3 nm through which light can be sufficiently transmitted.
  • the catalyst layer 13 may cover only part of the surface of the semiconductor thin film 12 .
  • a second semiconductor thin film 14 may be provided between the semiconductor thin film 12 and the catalyst layer 13 . That is, the semiconductor photoelectrode of FIG. 2 has the catalyst layer 13 on the second semiconductor thin film 14 .
  • the catalyst layer 13 may cover only part of the surface of the second semiconductor thin film 14 .
  • a semiconductor thin film 12 is formed on an insulating or conductive substrate 11 .
  • the semiconductor thin film 12 may be formed using metal organic chemical vapor deposition (MOCVD).
  • a metal layer that will form the catalyst layer 13 is formed on the semiconductor thin film 12 .
  • the metal layer may be formed by vacuum-depositing a metal on the surface of the semiconductor thin film 12 .
  • the catalyst layer 13 is formed by oxidizing the metal layer by ozone oxidation.
  • the catalyst layer 13 may be formed by subjecting the semiconductor thin film on which the metal layer is formed to ozone treatment using a commercially available ozone cleaner.
  • the method for manufacturing the semiconductor photoelectrode shown in FIG. 4 is obtained by adding a step of forming a second semiconductor thin film to the method for manufacturing the semiconductor photoelectrode shown in FIG.
  • a semiconductor thin film 12 is formed on an insulating or conductive substrate 11 in step 1-1.
  • a second semiconductor thin film 14 is formed on the semiconductor thin film 12 in step 1-2.
  • the second semiconductor thin film 14 may be formed using the MOCVD method.
  • step 2 a metal layer that will form the catalyst layer 13 is formed on the second semiconductor thin film 14 .
  • step 3 the catalyst layer 13 is formed by oxidizing the metal layer by ozone oxidation.
  • Example 1 The semiconductor photoelectrode of Example 1 was produced using the production method shown in FIG.
  • step 1 an n-GaN semiconductor thin film was epitaxially grown on a sapphire substrate by MOCVD. Ammonia gas and trimethylgallium were used as growth raw materials, and hydrogen was used as a carrier gas sent into the growth furnace. Si was used as a dopant element.
  • the film thickness of n-GaN was set to 2 ⁇ m. Carrier density was 3 ⁇ 10 18 cm ⁇ 3 .
  • step 2 Ni with a film thickness of about 1 nm was vacuum-deposited on the n-GaN semiconductor thin film.
  • step 3 using a Filgen UV ozone cleaner UV253H, the semiconductor thin film with the Ni layer was subjected to ozone oxidation treatment by exposing it to an ozone concentration of about 200 ppm for 30 minutes under atmospheric pressure and room temperature to form NiO. .
  • TEM observation of the cross section of the sample revealed that the NiO film thickness was 2 nm.
  • the semiconductor photoelectrode of Example 1 was obtained through the above steps.
  • Example 2 The semiconductor photoelectrode of Example 2 was produced using the production method of FIG.
  • step 1-1 an n-GaN semiconductor thin film was epitaxially grown on the sapphire substrate by MOCVD.
  • Ammonia gas and trimethylgallium were used as growth raw materials, and hydrogen was used as a carrier gas sent into the growth furnace.
  • Si was used as a dopant element.
  • the film thickness of n-GaN was set to 2 ⁇ m.
  • Carrier density was 3 ⁇ 10 18 cm ⁇ 3 .
  • step 1-2 an Al 0.1 Ga 0.9 N semiconductor thin film was epitaxially grown on the n-GaN semiconductor thin film by MOCVD.
  • Ammonia gas, trimethylgallium, and trimethylaluminum were used as growth raw materials, and hydrogen was used as a carrier gas sent into the growth furnace.
  • step 2 Ni having a film thickness of about 1 nm was vacuum-deposited on the Al 0.1 Ga 0.9 N semiconductor thin film.
  • step 3 similarly to Example 1, the semiconductor thin film on which the Ni layer was formed was subjected to ozone oxidation treatment under atmospheric pressure and room temperature to form NiO.
  • TEM observation of the cross section of the sample revealed that the NiO film thickness was 2 nm.
  • the semiconductor photoelectrode of Example 2 was obtained through the above steps.
  • Example 3 The semiconductor photoelectrode of Example 3 was produced using the production method of FIG.
  • the second semiconductor thin film 14 is different from the second embodiment.
  • step 1-1 an n-GaN semiconductor thin film was epitaxially grown on the sapphire substrate by MOCVD.
  • Ammonia gas and trimethylgallium were used as growth raw materials, and hydrogen was used as a carrier gas sent into the growth furnace.
  • Si was used as a dopant element.
  • the film thickness of n-GaN was set to 2 ⁇ m.
  • Carrier density was 3 ⁇ 10 18 cm ⁇ 3 .
  • step 1-2 an In 0.05 Ga 0.95 N semiconductor thin film was epitaxially grown on the n-GaN semiconductor thin film by MOCVD.
  • Ammonia gas, trimethylgallium, and trimethylindium were used as growth raw materials, and hydrogen was used as a carrier gas sent into the growth furnace.
  • step 2 Ni having a film thickness of about 1 nm was vacuum-deposited on the In 0.05 Ga 0.95 N semiconductor thin film.
  • step 3 similarly to Example 1, the semiconductor thin film on which the Ni layer was formed was subjected to ozone oxidation treatment under atmospheric pressure and room temperature to form NiO.
  • TEM observation of the cross section of the sample revealed that the NiO film thickness was 2 nm.
  • the semiconductor photoelectrode of Example 3 was obtained through the above steps.
  • the apparatus in FIG. 5 includes an oxidation tank 110 and a reduction tank 120.
  • the oxidation tank 110 contains an aqueous solution 111 and an oxidation electrode 112 is contained in the aqueous solution 111 .
  • An aqueous solution 121 is placed in the reduction tank 120 , and a reduction electrode 122 is placed in the aqueous solution 121 .
  • a 1 mol/l sodium hydroxide aqueous solution was used as the aqueous solution 111 in the oxidation tank 110 .
  • a potassium hydroxide aqueous solution or hydrochloric acid may be used as the aqueous solution 111.
  • a semiconductor photoelectrode to be tested was used as the oxidation electrode 112 .
  • the n-GaN surface was scribed, a conductive wire was connected to a portion of the surface, and soldered using indium.
  • An oxidation electrode 112 covered with an epoxy resin was installed so as not to be exposed.
  • a 0.5 mol/l potassium hydrogen carbonate aqueous solution was used as the aqueous solution 121 in the reduction tank 120 .
  • a sodium bicarbonate aqueous solution, a potassium chloride aqueous solution, or a sodium chloride aqueous solution may be used.
  • the reduction electrode 122 may be any metal or metal compound. Nickel, iron, gold, silver, copper, indium, or titanium, for example, may be used as the reduction electrode 122 .
  • the oxidation tank 110 and the reduction tank 120 are connected via the proton membrane 130 .
  • Protons generated in the oxidation tank 110 diffuse through the proton membrane 130 to the reduction tank 120 .
  • Nafion (registered trademark) was used for the proton membrane 130 .
  • Nafion is a perfluorocarbon material composed of a hydrophobic Teflon skeleton composed of carbon-fluorine and a perfluoro side chain having a sulfonic acid group.
  • the oxidation electrode 112 and the reduction electrode 122 are electrically connected by a conducting wire 132 , and electrons move from the oxidation electrode 112 to the reduction electrode 122 .
  • a 300 W high pressure xenon lamp (illuminance 5 mW/cm 2 ) was used as the light source 140 .
  • the light source 140 may irradiate light having a wavelength that can be absorbed by the material forming the semiconductor photoelectrode provided as the oxidation electrode 112 .
  • the wavelength that the oxide electrode 112 can absorb is 365 nm or less.
  • a light source such as a xenon lamp, a mercury lamp, a halogen lamp, a pseudo-sunlight light source, or sunlight may be used, or a combination of these light sources may be used.
  • the light source 140 is fixed so as to face the NiO-formed surface of the semiconductor photoelectrode to be tested, which is installed as the oxidation electrode 112, and the semiconductor photoelectrode is uniformly exposed to the light. irradiated with light.
  • Table 1 shows the amount of oxygen/hydrogen gas generated with respect to the light irradiation time in Examples 1 to 3 and Comparative Examples 1 to 3. The amount of each gas produced is shown as normalized by the surface area of the semiconductor photoelectrode. In all cases, it was found that oxygen and hydrogen were generated during light irradiation.
  • Example 1 Compared to Comparative Example 1, in Example 1, the amount of production immediately after light irradiation was greater. It is considered that this is because the resistance generated at the interface between the semiconductor and NiO was reduced. Further, when comparing the production amount after 50 hours and 100 hours from the light irradiation, it was found that Example 1 had a smaller reduction in the production amount and a longer life than Comparative Example 1. It is considered that this is because distortion of each layer in the vicinity of the interface between the semiconductor and NiO is suppressed, and good adhesion can be maintained for a long time.
  • the method for manufacturing a semiconductor photoelectrode includes the first step of forming the semiconductor thin film 12 on the insulating or conductive substrate 11, and the formation of the metal layer on the surface of the semiconductor thin film 12. It has a second step and a third step of forming the catalyst layer 13 by oxidizing the metal layer by ozone oxidation.
  • ozone oxidation to oxidize the metal formed on the surface of the semiconductor thin film without heat history, the adhesion between the semiconductor thin film and the catalyst layer interface is improved. Thereby, the light energy conversion efficiency and life of the semiconductor photoelectrode can be improved.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
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PCT/JP2021/042024 2021-11-16 2021-11-16 半導体光電極の製造方法 Ceased WO2023089654A1 (ja)

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PCT/JP2021/042024 WO2023089654A1 (ja) 2021-11-16 2021-11-16 半導体光電極の製造方法
JP2023561948A JP7787436B2 (ja) 2021-11-16 2021-11-16 半導体光電極の製造方法

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014527579A (ja) * 2011-08-11 2014-10-16 トヨタ モーター エンジニアリング アンド マニュファクチャリング ノース アメリカ，インコーポレイティド 効率的な水酸化触媒及びエネルギー生成方法
JP2017101288A (ja) * 2015-12-02 2017-06-08 日本電信電話株式会社 半導体光電極
JP2020090690A (ja) * 2018-12-03 2020-06-11 日本電信電話株式会社 窒化物半導体光電極の製造方法
JP2020189265A (ja) * 2019-05-21 2020-11-26 国立大学法人 新潟大学 触媒の製造方法、金属酸化物の製造方法および触媒

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014527579A (ja) * 2011-08-11 2014-10-16 トヨタ モーター エンジニアリング アンド マニュファクチャリング ノース アメリカ，インコーポレイティド 効率的な水酸化触媒及びエネルギー生成方法
JP2017101288A (ja) * 2015-12-02 2017-06-08 日本電信電話株式会社 半導体光電極
JP2020090690A (ja) * 2018-12-03 2020-06-11 日本電信電話株式会社 窒化物半導体光電極の製造方法
JP2020189265A (ja) * 2019-05-21 2020-11-26 国立大学法人 新潟大学 触媒の製造方法、金属酸化物の製造方法および触媒

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