Metal oxyhidride epitaxy and creation of fascinating electronic/dielectric properties

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01629
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 26020:Inorganic materials and properties-related
• Research Institution: National Institute for Materials Science
• Principal Investigator: OHSAWA Takeo 国立研究開発法人物質・材料研究機構, 電子・光機能材料研究センター, 主幹研究員 (00450289)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 酸水素化物 / エピタキシャル薄膜 / 電子物性 / 光電子分光 / 質量分析

Outline of Final Research Achievements

The objective was to elucidate fundamental electrical conductivity in epitaxial thin films of nanoscale thick oxyhydrides, which are single-crystal films free from grain boundary scattering that is unavoidable in bulk materials. The approach involved the oxyhydrogenation of anatase-type titanium dioxide thin films epitaxially grown by plasma-assisted molecular beam epitaxy. Hydrogen plasma irradiation successfully introduced hydrogen from the thin film surfaces. As a result, the electron concentration could be controlled, successfully inducing an insulator-metal transition. It was observed that these electron concentrations were comparable to the hydrogen concentrations quantified by mass spectrometry, indicating that transparent electrical conductivity could be achieved and controlled through oxyhydrogenation. This technique was extended to complex oxides, and metallic temperature dependence was successfully obtained in oxyhydrogenated thin films of lattice-relaxed barium titanate.

Free Research Field

無機材料物性

Academic Significance and Societal Importance of the Research Achievements

バルク体では作製が困難であった前周期遷移金属酸化物の酸水素化を、ナノスケール厚のエピタキシャル薄膜で成功した。従来のようなカチオン不純物を必要とせず、薄膜の水素化だけによる透明伝導性の発現と制御を見出した。