Spectral dynamics of shift current in ferroelectric semiconductor SbSI


Photoexcitation in solids brings about transitions of electrons/ holes between different electronic bands. If the solid lacks an inversion symmetry, these electronic transitions support spontaneous photocurrent due to the geometric phase of the constituting electronic bands: the Berry connection. This photocurrent, termed shift current, is expected to emerge on the timescale of primary photoexcitation process. We observe ultrafast evolution of the shift current in a prototypical ferroelectric semiconductor antimony sulfur iodide (SbSI) by detecting emitted terahertz electromagnetic waves. By sweeping the excitation photon energy across the bandgap, ultrafast electron dynamics as a source of terahertz emission abruptly changes its nature, reflecting a contribution of Berry connection on interband optical transition. The shift excitation carries a net charge flow and is followed by a swing over of the electron cloud on a subpicosecond timescale. Understanding these substantive characters of the shift current with the help of first-principles calculation will pave the way for its application to ultrafast sensors and solar cells.

Bulk matter, Ferroelectricity, Photovoltaic effect, Picosecond techniques, Solar cells, antimony derivative, antimony sulfur iodide, iodine derivative, sulfur derivative, unclassified drug, Article, dynamics, electric current, electromagnetic radiation, electron transport, factor analysis, ferroelectric semiconductor, mathematical computing, photon, priority journal, terahertz radiation
Sotome, M., Nakamura, M., Fujioka, J., Ogino, M., Kaneko, Y., Morimoto, T., et al. (2019). Spectral dynamics of shift current in ferroelectric semiconductor SbSI (Version publishedVersion, Vol. 116). Version publishedVersion, Vol. 116. Washington : National Academy of Sciences. https://doi.org//10.1073/pnas.1802427116