Depinning of Fermi Level by Interface Structure Control

2020 Fiscal Year Final Research Report

• Project/Area Number: 18H03830
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Medium-sized Section 26:Materials engineering and related fields
• Research Institution: Tohoku University
• Principal Investigator: Koike Junichi 東北大学, 工学研究科, 教授 (10261588)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 半導体 / 金属 / 界面 / コンタクト / 抵抗

Outline of Final Research Achievements

We found that Co-Ti can decrease the growth rate of Co monosilicide (CoSi) that had an epitaxial relation with Si. By overlaying SiO2, SBH could be decreased from 0.7 to 0.3 eV. When TiO2 or TiNbO2 was used in place of SiO2, their small band offset could bring about a low SBH of 0.3 eV consistently. However, apparent contact resistivity remained high because of their high resistance. We also investigated the contact property of n-GaN. The growth of epitaxial Ga2O3 oxide on GaN could reduce DIGS, while the insulating property of the oxide could reduce MIGS, which brought about a very low SBH of 0.1 eV and three-orders lower contact resistivity than the samples without the oxide.

Free Research Field

材料工学

Academic Significance and Societal Importance of the Research Achievements

金属と半導体の界面を整合界面にすることと、バンドオフセットが小さい酸化物を利用することでショットキー障壁高さが低減できるが、、酸化物の抵抗が高いことによる接触抵抗率の高止まりを明確に示した。また、良導体酸化物を利用することの可能性を示した。さらに、GaNにおいて界面構造欠陥由来（DIGS)と金属由来（MIGS)の界面準位を一挙に低減できる酸化物としてβ-Ga2O3の有効性を示した。このように、界面整合性、金属電子の染み出し、界面層の抵抗がSBHと接触抵抗率に及ぼす影響を一つずつ解明し、今後の超微細高速半導体デバイスのコンタクト材料開発の先鞭をつけた。