The ultrafast dynamics of charge carriers in solids plays a pivotal role in emerging optoelectronics, photonics, energy harvesting, and quantum technology applications. However, the investigation and direct visualization of such nonequilibrium phenomena remains as a long-standing challenge, owing to the nanometer-femtosecond spatiotemporal scales at which the charge carriers evolve. Here, we propose and demonstrate an interaction mechanism enabling nanoscale imaging of the femtosecond dynamics of charge carriers in solids. This imaging modality, which we name charge dynamics electron microscopy (CDEM), exploits the strong interaction of free-electron pulses with terahertz (THz) near fields produced by the moving charges in an ultrafast scanning transmission electron microscope. The measured free-electron energy at different spatiotemporal coordinates allows us to directly retrieve the THz near-field amplitude and phase, from which we reconstruct movies of the generated charges by comparison to microscopic theory. The CDEM technique thus allows us to investigate previously inaccessible spatiotemporal regimes of charge dynamics in solids, providing insight into the photo-Dember effect and showing oscillations of photogenerated electron-hole distributions inside a semiconductor. Our work facilitates the exploration of a wide range of previously inaccessible charge-transport phenomena in condensed matter using ultrafast electron microscopy.

Yannai, M., Dahan, R., Gorlach, A., Adiv, Y., Wang, K., Madan, I., et al. (2023). Ultrafast Electron Microscopy of Nanoscale Charge Dynamics in Semiconductors. ACS NANO, 17(4), 3645-3656 [10.1021/acsnano.2c10481].

Ultrafast Electron Microscopy of Nanoscale Charge Dynamics in Semiconductors

Vanacore G. M.;
2023

Abstract

The ultrafast dynamics of charge carriers in solids plays a pivotal role in emerging optoelectronics, photonics, energy harvesting, and quantum technology applications. However, the investigation and direct visualization of such nonequilibrium phenomena remains as a long-standing challenge, owing to the nanometer-femtosecond spatiotemporal scales at which the charge carriers evolve. Here, we propose and demonstrate an interaction mechanism enabling nanoscale imaging of the femtosecond dynamics of charge carriers in solids. This imaging modality, which we name charge dynamics electron microscopy (CDEM), exploits the strong interaction of free-electron pulses with terahertz (THz) near fields produced by the moving charges in an ultrafast scanning transmission electron microscope. The measured free-electron energy at different spatiotemporal coordinates allows us to directly retrieve the THz near-field amplitude and phase, from which we reconstruct movies of the generated charges by comparison to microscopic theory. The CDEM technique thus allows us to investigate previously inaccessible spatiotemporal regimes of charge dynamics in solids, providing insight into the photo-Dember effect and showing oscillations of photogenerated electron-hole distributions inside a semiconductor. Our work facilitates the exploration of a wide range of previously inaccessible charge-transport phenomena in condensed matter using ultrafast electron microscopy.
Articolo in rivista - Articolo scientifico
Dember effect; electron−hole dynamics; terahertz emission; terahertz near field imaging; terahertz spectroscopy; ultrafast charge transport; ultrafast electron microscopy;
English
3-feb-2023
2023
17
4
3645
3656
none
Yannai, M., Dahan, R., Gorlach, A., Adiv, Y., Wang, K., Madan, I., et al. (2023). Ultrafast Electron Microscopy of Nanoscale Charge Dynamics in Semiconductors. ACS NANO, 17(4), 3645-3656 [10.1021/acsnano.2c10481].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/406176
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