Study on the rate limiting process of the gate-induced phase transition and the speed limit of the phase transition transistor

2022 Fiscal Year Final Research Report

• Project/Area Number: 20H02615
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 29020:Thin film/surface and interfacial physical properties-related
• Research Institution: Kyushu University
• Principal Investigator: Yajima Takeaki 九州大学, システム情報科学研究院, 准教授 (10644346)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 金属絶縁体転移 / 微細化 / ３端子素子 / モットトランジスタ / 過渡特性 / ドメイン成長

Outline of Final Research Achievements

We have studied miniaturization and speed-up of 3-terminal devices using VO2, a metal-insulator transition material, as a channel. In long-channel devices, the transition is continuous with respect to the gate voltage, and as the drain voltage is increased, the transition steepens due to Joule heating effects. On the other hand, when the device is miniaturized, the transition becomes steeper (discontinuous) regardless of the drain voltage, indicating that the transition of the VO2 channel has become single-domain. Furthermore, the transient characteristics show an exponential increase in speed with gate voltage, and the amount of change is extremely large and cannot be explained without considering the collective nature of VO2. As described above, a comprehensive understanding of the static and transient characteristics of VO2 3-terminal devices was obtained.

Free Research Field

酸化物エレクトロニクス

Academic Significance and Societal Importance of the Research Achievements

ゲート電圧によって誘起される相転移について、ドレイン電圧の影響、微細化の影響、過渡特性といった３つの側面から包括的な理解が得られた。近年液体ゲートを用いた相転移の研究が進んでいるが、イオン液体の取り扱いの難しさからこのような系統的な実験は進んでいないのが現状である。本研究は、我々独自の固体ゲート素子を用いることで、相転移チャネルを用いた３端子素子についての理論・モデルを構築し、実験的に検証することで、今後の３端子デバイス研究の基盤を構築するものだといえる。