2020 Fiscal Year Final Research Report

New Developments in Oxide Semiconductors; Material Science and Device Technology of Narrow-Gap Wurtzite Oxides

Research Project

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Project/Area Number	17H01315
Research Category	Grant-in-Aid for Scientific Research (A)
Allocation Type	Single-year Grants
Section	一般
Research Field	Inorganic materials/Physical properties
Research Institution	Tohoku University
Principal Investigator	Omata Takahisa 東北大学, 多元物質科学研究所, 教授 (80267640)
Co-Investigator(Kenkyū-buntansha)	鈴木一誓東北大学, 多元物質科学研究所, 助教 (60821717) 佃諭志東北大学, 多元物質科学研究所, 講師 (00451633) 喜多正雄富山高等専門学校, その他部局等, 准教授 (00413758)
Project Period (FY)	2017-04-01 – 2021-03-31
Keywords	結晶成長 / セラミックス / 先端機能デバイス / 光物性
Outline of Final Research Achievements	In this study, we investigated mist CVD and PLD methods for the fabrication of β-NaGaO2 thin films, which are precursors of β-CuGaO2. For the mist-CVD method, we developed a new deposition apparatus. By using the new apparatus, deposition of β-NaGaO2 thin film with nearly stoichiometric composition (average composition of Na:Ga=1:0.91) and homogeneous morphology was successful. For the PLD method, we succeeded in depositing β-NaGaO2 thin film with stoichiometric composition and homogeneous microstructure by reducing the distance between target and substrate. XPS analysis revealed that the band alignment of β-CuGaO2 and Al-doped ZnO is Type II, and the electrons and holes generated by photoexcitation are separated, indicating that the p/n junctions of β-CuGaO2 with ZnO is applicable to thin-film solar cells.
Free Research Field	無機材料の化学
Academic Significance and Societal Importance of the Research Achievements	薄膜太陽電池の光吸収材料では，有害なカドミウムを含むCdTeや希少なインジウムを含むCu(InGa)Se2などのカルコゲナイド半導体の独壇場となっている。本研究では資源が豊富で安全な元素から成る酸化物半導体β-CuGaO2を太陽電池へと展開するのに必要な，化学量論組成のβ-NaGaO2前駆体薄膜の作製に目処をつけ，薄膜太陽電池の実現に向け着実な進歩を遂げている。また，p型β-CuGaO2とn型ZnOとが太陽電池に適切なType-II型接合を作ることを明らかにしており，β-CuGaO2が太陽電池材料として有望な材料であることを実験的に検証しており，学術的にも社会的にも意義ある成果をあげている。