Reduction of contact resistance and demonstration of nitrogen-polar AlN field-effect transistors

2018 Fiscal Year Final Research Report

• Project/Area Number: 17K14110
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Crystal engineering
• Research Institution: University of Tsukuba
• Principal Investigator: Hironori Okumura 筑波大学, 数理物質系, 助教 (80756750)
• Research Collaborator: UEDONO Akira 筑波大学, 数理物質系, 教授 ; Oshima Takayoshi 佐賀大学, 理工学部, 准教授 ; Palacios Tomas MIT大学, Electrical engineering and Computer Science, 教授 ; Suihkonen Sami Aalto大学, Electronics and Nanoengineering, Scientist ; Kakanakova Anelia Linkoping大学, Physics Chemistry and Biology, 准教授
• Project Period (FY): 2017-04-01 – 2019-03-31
• Keywords: パワーデバイス / 窒化物半導体 / 結晶成長 / 窒素極性面 / 電界効果トランジスタ / 有機金属気相成長 / 接触抵抗

Outline of Final Research Achievements

In this work, we aimed to develop Aluminum-nitride (AlN) based electrical devices, which have attracted much attention for high-frequency and high-power applications. AlN-based devices have suffered from the high contact resistances and low carrier concentrations because of the large band-gap of AlN (6.1 eV). To solve these issues, we challenged to fabricate the new structure of nitrogen-polar AlN polarization field-effect transistors (POLFETs).
(i) High crystalline-quality AlN films with a nitrogen-polar orientation were grown by metal-organic vapor-phase deposition system.
(ii) We firstly achieved the demonstration of nitrogen-polar FETs by controlling the unintentionally doped impurities.

Free Research Field

窒化物半導体の結晶成長と電子素子作製

Academic Significance and Societal Importance of the Research Achievements

本研究は、AlNの物性を活かした高耐圧素子の実現を目指す、実用的な研究である。時には絶縁体にも分類される、超ワイドバンドギャップ半導体のAlNを用いた素子を作製することは、半導体物性の物理限界を知る研究になり、学術的に大きな意義がある。本研究により、高性能AlNトランジスタを実現できたことで、新しい高耐圧素子用材料の分野開拓および普及に大きく貢献できると期待する。