Investigation and controlling of a quasi-dopant effect at a ferroelectric charged surface and interface

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K04495
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 21050:Electric and electronic materials-related
• Research Institution: University of Hyogo
• Principal Investigator: Nakashima Seiji 兵庫県立大学, 工学研究科, 准教授 (80552702)
• Co-Investigator(Kenkyū-buntansha): 藤澤 浩訓 兵庫県立大学, 工学研究科, 教授 (30285340)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 強誘電体 / 半導体物性 / 擬似ドーパント / 帯電ドメイン壁 / バンド構造

Outline of Final Research Achievements

In this research, we have investigated the effect of band modulation due to spontaneous polarization switching, which is indispensable when a ferroelectric is used as a semiconductor. Firstly, the effect of Mn on the band structure in the Au/Mn-doped BiFeO3 (BFMO) structure have been clarified. In addition, the bulk photovoltaic effect has been investigated in detail as a property of the ferroelectric semiconductor, and it was shown that the band structure modulation greatly affects the open circuit voltage. As a result, a huge voltage of 852V at -193 °C have been successfully generated. Secondary, the band modulation due to spontaneous polarization switching in the graphene/BFMO structure has been clarified by a photoemission electron microscope. Thirdly, the charged DW, which is the ferroelectric/ferroelectric interface, can be artificial introduced to an arbitrary position in the BFMO film, and confirmed its conductivity modulation.

Free Research Field

固体電子工学

Academic Significance and Societal Importance of the Research Achievements

近年、半導体デバイスの高集積化が限界に達しつつある。加えて機械学習の発展により脳型コンピューティングのニーズが高まっている。本研究の成果はこれまで絶縁体として扱われてきた強誘電体を半導体として用いることで、今までにない新機能をもつデバイスの創出に寄与するものである。特に強誘電体のバルク光起電力効果は光メモリ、高効率太陽電池の創出が期待でき、自発分極による自身の導電性変調はインメモリコンピューティングを実現する導電性スイッチングメモリへの応用に期待できる。