First-principles analysis of modification of dielectric response at oxide interfaces

2018 Fiscal Year Final Research Report

• Project/Area Number: 15K20953
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Inorganic materials/Physical properties; Thin film/Surface and interfacial physical properties
• Research Institution: The University of Tokyo
• Principal Investigator: Kasamatsu Shusuke 東京大学, 物性研究所, 助教 (60639160)
• Research Collaborator: SUGINO Osamu
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: 第一原理計算 / 統計熱力学 / 誘電率 / 界面 / 格子欠陥

Outline of Final Research Achievements

In this project, we started with the optimization and development of the "orbital-separation approach" program code for performing first-principles simulation of metal/insulator/metal capacitors under bias in closed-circuit and open-circuit boundary conditions. We then used the developed code to simulate a ferroelectric/paraelectric bilayer capacitor under bias. We found that "negative capacitance" emerges as a result of the dynamics of the ferroelectric polarization domains.

Furthermore, we developed a simulation framework for directly combining first-principles calculations with replica-exchange Monte Carlo sampling of configurational disorder in solids. This was used to dramatically increase the prediction accuracy of the distribution of defects at oxide interfaces.

Free Research Field

計算物質・材料科学

Academic Significance and Societal Importance of the Research Achievements

「負のキャパシタンス」は従来の半導体のスケーリング則を打ち破り、ナノエレクトロニクスのさらなる発展を実現するための有望な現象とされている。本研究によってその起源を明らかにしたことで、実用化により一層近づいたと言える。

また、欠陥分布の予測ソフトウェアは今後、欠陥を積極的に利用した機能材料の開発に不可欠なものになると考える。