Fabrication of novel quantum/classical devices based on excitons

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K21978
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 21:Electrical and electronic engineering and related fields
• Research Institution: Kyushu University
• Principal Investigator: Itagaki Naho 九州大学, システム情報科学研究院, 教授 (60579100)
• Project Period (FY): 2019-06-28 – 2021-03-31
• Keywords: 酸化物半導体 / スパッタリング / 量子構造 / エキシトン

Outline of Final Research Achievements

We developed new semiconducting materials, (ZnO)x(InN)1-x (hereafter called ZION) for exciton transistors, synthesized by sputter epitaxy. The large exciton binding energy enables excitonic devices that are operational at room temperature. The large piezoelectric constant enhances the spatial separation of electrons and holes in quantum wells and thus elongates exciton lifetime. Fabrication of single crystalline ZION films, however, has been challenging because no bulk crystals of ZION exist. In this project, we succeeded in the growth of world’s first single crystalline ZION on 18%-lattice-mismatched sapphire substrate, in which the films grew in a new mode of heteroepitaxy, “inverse Stranski-Krastanov mode”, where high-density three dimensional (3D) islands initially form and two-dimensional (2D) layers subsequently grow on the 3D islands. Furthermore, we succeeded in optical switching of exciton transistors with ZION/ZnO QWs.

Free Research Field

電子材料，プラズマエレクトロニクス

Academic Significance and Societal Importance of the Research Achievements

本研究は，代表者オリジナルのシーズ技術を背景に，エキシトンを情報担体に進化させ，革新的古典／量子デバイスの創製を目指したものである．エキシトンを「電子－正孔が再結合する過程 (=中間状態）としての準粒子」として扱い，受発光を伴うその生成と消滅に着目した物性解明・工学的応用を行ってきたこれまでのエキシトン研究を転換させる点で，学術的意義を有する．本研究は，新学術分野「エキシトニクス」の創成という学術的新規性に加え，古典／量子デバイスを利用した情報通信ネットワークの高度化への寄与等，実用的観点からも意義を有する．