2026-03-07 東京大学
強誘電体のフォノンによる光電流生成を示す模式図
＜関連情報＞
- https://www.t.u-tokyo.ac.jp/press/pr2026-03-07-001
- https://www.science.org/doi/10.1126/sciadv.adw9796
強誘電体半導体SbSIにおけるフォノン励起による大きなテラヘルツ光起電力効果の増強 Large terahertz photovoltaic effect enhanced by phonon excitations in ferroelectric semiconductor SbSI
Yoshihiro Okamura, Guang-Yu Guo, Yoshio Kaneko, Masao Nakamura, […] , and Youtarou Takahashi
Science Advances Published:6 Mar 2026
Abstract
Quantum geometry of Bloch electron in crystalline solids produces various exotic quantum phenomena. The shift current photovoltaic effect driven by the photo creation of quasiparticle is one such emerging example that enables the conversion from terahertz photon into dc charge current with absence of dissipative photocarrier. Despite wide-ranging potential applications, however, the fundamental nature of terahertz photovoltaic response has remained elusive. Here, we show the large photocurrent generation driven by terahertz phonons (<10 milli–electron volts) in ferroelectric semiconductor SbSI with the electronic bandgap of 2.3 electron volts. Zero-bias terahertz photocurrent is found to be resonantly enhanced by optical phonons. Its generation efficiency is larger than that for the direct interband transition and is comparable to the electronic shift current in Weyl semimetal TaAs. The theoretical scaling law of terahertz shift current and first-principles calculation reasonably explain these observations. The present work establishes the universality and high efficiency of phonon-driven shift current, opening the pathway to terahertz technology based on quantum geometry.
