scholarly journals Spectral dynamics of shift current in ferroelectric semiconductor SbSI

2019 ◽  
Vol 116 (6) ◽  
pp. 1929-1933 ◽  
Author(s):  
M. Sotome ◽  
M. Nakamura ◽  
J. Fujioka ◽  
M. Ogino ◽  
Y. Kaneko ◽  
...  

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.

2013 ◽  
Vol 815 ◽  
pp. 148-153
Author(s):  
Jun Jie Shi ◽  
Tie Cheng Zhou ◽  
Hong Xia Zhong ◽  
Xin He Jiang ◽  
Pu Huang

The InGaN nanowires (NWs) have attracted intense attention for their huge potential in applications such as light emitting diodes, laser diodes and solar cells. Although lots of work are focused on improving their optical performance, little is known about the influence of the In distribution and the surface states on the microscopic light emission mechanism. In order to give an atomic level understanding, we investigate the electronic structures of the wurtziteGa-rich InGaN NWs with different In distributions using first-principles calculations. We find that the In-atoms are apt to distribute on the surface of the NWs and the short surface In-N chains can be easily formed. For the unsaturated NWs, several new bands are induced by the surface states, which can be modified by the surface In microstructures. The randomly formed surface In-N chains can highly localize the electrons/holes at the band edges and dominate the interband optical transition. For the saturated NWs, the band edges are determined by the inner atoms. Our work is useful to improve the performance of the InGaN NW-based optoelectronic devices.


1981 ◽  
Vol 42 (C6) ◽  
pp. C6-625-C6-627 ◽  
Author(s):  
P. E. Van Camp ◽  
V. E. Van Doren ◽  
J. T. Devreese

2021 ◽  
Vol 27 (6) ◽  
Author(s):  
Wen-Guang Li ◽  
Yun-Dan Gan ◽  
Zhi-Xin Bai ◽  
Ming-Jian Zhang ◽  
Fu-Sheng Liu ◽  
...  

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