Study on High Field Carrier Transport in Gallium Nitride

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K20423
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0302:Electrical and electronic engineering and related fields
• Research Institution: The University of Tokyo
• Principal Investigator: Maeda Takuya 東京大学, 大学院工学系研究科(工学部), 講師 (20965694)
• Project Period (FY): 2022-08-31 – 2024-03-31
• Keywords: 窒化ガリウム(GaN) / 高周波トランジスタ / ドリフト速度 / 二次元電子ガス(2DEG)

Outline of Final Research Achievements

In this study, we systematically examined the drift velocity of two-dimensional electron gas (2DEG) induced by polarization at the AlGaN/GaN heterojunction interface, aiming for an advanced design and understanding of the characteristics of gallium nitride (GaN)-based high-frequency transistors. To minimize contact resistance, we fabricated transmission line method (TLM) test devices with embedded regrown n+GaN. While paying attention to minimizing self-heating through pulse current-voltage (I-V) measurements with pulse widths of 1 us or less, we obtained I-V characteristics for various dimensions (width, length) of current paths. Upon analyzing the I-V characteristics and extracting the velocity-electric field characteristics, we successfully obtained consistent velocity-electric field characteristics regardless of dimensions.

Free Research Field

電子工学

Academic Significance and Societal Importance of the Research Achievements

本研究で得られた結果は，AlGaN/GaNヘテロ接合における2DEGのドリフト速度-電界特性の決定版というべき結果である．様々なAl組成の素子を作製し，どの特性を詳細かつ系統的に調べることで，電界依存性や電子濃度依存性，温度依存性を包括的に明らかにすることに成功した．特に，測定用素子の構造や測定手法を工夫することで，誤差要因を徹底的に排除し，非常に精度のよい値が得られたことが特色・独自性である．これらの結果は，GaN高周波デバイスの高電界輸送を理解する際に非常に有益であり，次世代高周波通信を担うデバイスの性能理解に大きく役立つ結果である．