Elucidation of electromagnetic wave emission responses in semiconductor crystals under the coexistence of different kinds of terahertz-range transient phenomena

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K03497
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13020:Semiconductors, optical properties of condensed matter and atomic physics-related
• Research Institution: Osaka Institute of Technology (2020); University of Hyogo (2018-2019)
• Principal Investigator: Hasegawa Takayuki 大阪工業大学, 工学部, 講師 (00533184)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: テラヘルツ電磁波 / キャリア輸送 / プラズモン / コヒーレントフォノン / キャリアダイナミクス / 超高速現象

Outline of Final Research Achievements

This study investigated terahertz wave emissions under the coexistence of different kinds of terahertz-range transient phenomena in GaAs epitaxial thin films. The systematic measurements of terahertz waveforms at various excitation conditions were carried out, and the experimental results were analyzed by the consideration of coupled oscillations of photoexcited plasmons and longitudinal optical phonons. The present analysis elucidates the superposition of the terahertz wave signals originating from the non-equilibrium carrier transport and the longitudinal optical phonon-plasmon coupled mode. Moreover, it was found that the transport property of electrons depending on the internal electric field is one of the important factors to characterize the terahertz waveform.

Free Research Field

光物性

Academic Significance and Societal Importance of the Research Achievements

テラヘルツ電磁波の発生方法は多数存在するが、半導体表面の過渡現象を利用する方法は、デバイス加工や複雑なレーザー系を必要としない等の利点がある。本研究で明らかにした異種過渡現象共存下のテラヘルツ電磁波放射の物理描像は、テラヘルツ電磁波発生機構のさらなる理解につながるものであり、学術的意義がある。また、テラヘルツ電磁波放射の制御に関する新知見は、本発生機構に基づくテラヘルツ電磁波応用の発展に貢献することが期待される。