Development of basic science and technology for nitride semiconductor optical devices by controlling phonon functions

2019 Fiscal Year Final Research Report

• Project/Area Number: 17H02772
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Crystal engineering
• Research Institution: Chiba University
• Principal Investigator: Ishitani Yoshihiro 千葉大学, 大学院工学研究院, 教授 (60291481)
• Co-Investigator(Kenkyū-buntansha): 三宅 秀人 三重大学, 地域イノベーション学研究科, 教授 (70209881)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: フォノン / 励起子ダイダイナミクス / 顕微ラマン分光 / THz輻射 / 縦光学モード / フォノン輸送

Outline of Final Research Achievements

The operating characteristics of optical devices deteriorate owing to temperature rise. It was shown that phonon transport, which is the essence of heat, can be characterized by Raman imaging by simultaneous irradiation of two lasers. In particular, heat transport was found to be blocked by the misfit dislocations located in the vicinity of interface. Although the occupation factor of longitudinal optical (LO) phonon is low, the control of this phonon is the most important factor. It was also found that the increase in residual electrons can suppress the influence of the phonon process to a certain extent. We have observed LO phonon resonant THz-IR radiation from surface metal stripe structures, which indicates that there is a possibility of cooling for LO phonon. These results are thought to be the basis of future phonon transport control and its characterization methods.

Free Research Field

半導体工学

Academic Significance and Societal Importance of the Research Achievements

光・電子デバイスの熱制御ではモードを区別したフォノン輸送解析が必要であり，本研究で構築した2波長レーザ同時照射ラマンイメージングは重要な制御対象である縦光学(LO)フォノンを区別した熱輸送評価が可能である。本研究で構築した励起子解析コードは励起空間の全エネルギー収支を取り入れたダイナミクス解析コードで，新たな発光効率解析手法の基盤となる。表面マイクロ構造によるLOフォノン共鳴赤外輻射の観測はフォノンによる新規赤外-THz輻射デバイスの構築の他，LOフォノンに特化した冷却の可能性を示し，デバイス冷却機構の方式に多様性をもたせる。本研究は，デバイスの省エネ化や高機能化の基礎物理開拓に資する。