[23a-B205-1~11] 13.2 Exploratory Materials, Physical Properties, Devices

11:00 AM - 11:15 AM JST(2:00 AM - 2:15 AM UTC)Presentation by Applicant for JSAP Young Scientists Presentation Award

[23a-B205-8] Room-temperature anisotropic conductivity dynamics in photoexcited silicon

〇(M2)Ami Shirai¹, Yuta Murotani¹, Tomohiro Fujimoto¹, Natsuki Kanda^1,2, Ryusuke Matsunaga¹ (1.ISSP, The Univ. of Tokyo, 2.RAP, RIKEN)

Keywords:

time-resolved spectroscopy,Terahertz spectroscopy,Pump-probe spectroscopy

Photoexcited carriers in silicon can induce anisotropic conductivity due to the valley polarization of electrons or anisotropic dispersion near the Γ-point for holes. While the anisotropic distribution of carriers in momentum space has been investigated by time-resolved reflectivity measurement or cyclotron resonant spectroscopy, the dynamics and microscopic mechanisms are still elusive. In this work, by using optical pump and polarization-resolved terahertz probe spectroscopy, we realized direct observation of the transient anisotropic conductivity of photoexcited carriers near the indirect band gap. We successfully discriminated the contributions of the valley polarization of the electrons and of the anisotropic hole dispersion, and revealed each dynamics and their dependence on the incident photon energy at room temperature. The results pave the pathway for valleytronics in silicon at room temperature.