Sputter Epitaxy of high-quality oxynitride semiconductors for optical switching devices

2018 Fiscal Year Final Research Report

• Project/Area Number: 15H05431
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Plasma electronics
• Research Institution: Kyushu University
• Principal Investigator: Itagaki Naho 九州大学, システム情報科学研究院, 准教授 (60579100)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: スパッタリング / エキシトントランジスタ / 酸窒化インジウム亜鉛 / 量子井戸 / 逆Stranski-Krastanovモード / 格子不整合 / エピタキシー

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

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，E/O変換の小型化と高速化を同時に達成するエキシトントランジスタの室温動作可能性を示したものである．これが実用化されれば，光電子集積回路の実現を可能にし，従来エレクトロニクスでは達成し得ない高速・低消費電力LSIに発展すると期待される．また，本研究で用いた単結晶成長法は，代表者が発見した「逆SKモード」の成長機構に立脚した斬新な手法である．薄膜材料と基板の組み合わせ自由度を飛躍的に高める，従来にない革新材料・デバイスの創出につながるものである．これが普遍化すれば，今後様々な薄膜形成に革新をもたらすと期待される．