Material Design of High Mobility Transparent Conductive Films

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05339
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 29020:Thin film/surface and interfacial physical properties-related
• Research Institution: National Institute of Advanced Industrial Science and Technology
• Principal Investigator: Koida Takashi 国立研究開発法人産業技術総合研究所, エネルギー・環境領域, 研究グループ長 (70415678)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 酸化物半導体 / 透明導電膜 / 酸化インジウム / 移動度 / ドーピング / 遷移金属 / 水素 / 固相成長

Outline of Final Research Achievements

Doping phenomena were studied in indium oxide semiconductors to obtain guidelines for the creation of high-mobility transparent electrodes. Experimental results showed that thin films with high mobility were obtained depending on the impurity added, and various characterization tools were used to elucidate the factors responsible for the different mobility levels. In particular, thin films co-doped with Ce and H achieve significantly higher mobility than ITO thin films commonly used in the market. The reason for this is found to be not the small effective mass of electrons, but the effective suppression of electron scattering: Ce has a high dissociation energy with oxygen and suppresses the formation of oxygen vacancies, the lattice distortion caused by Ce addition is also suppressed due to the close ionic radius with In, and the Ce 4f level is higher than the Fermi energy, which is thought to suppress the interaction with free electrons.

Free Research Field

酸化物エレクトロニクス、太陽電池

Academic Significance and Societal Importance of the Research Achievements

本成果は、透明性と高い導電性を兼ね備えた材料の開発に新たな視点を与え、エネルギー変換デバイスの性能向上に寄与する。また、一般的なホール測定に加え、赤外分光、昇温脱離分析、硬X線電子分光法により、電子の有効質量、キャリア濃度、緩和時間、欠陥状態、そして電子状態を調べる詳細な物性解析手法の確立により、材料設計への効果的なアプローチが可能となる。