Unlike in bulk materials, energy transport in low-dimensional and nanoscale systems may be governed by a coherent ballistic behavior of lattice vibrations, the phonons. If dominant, such behavior would determine the mechanism for transport and relaxation in various energy-conversion applications. In order to study this coherent limit, both the spatial and temporal resolutions must be sufficient for the length-time scales involved. Here, we report observation of the lattice dynamics in nanoscale quantum dots of gallium arsenide using ultrafast electron diffraction. By varying the dot size from h = 11 to 46 nm, the length scale effect was examined, together with the temporal change. When the dot size is smaller than the inelastic phonon mean-free path, the energy remains localized in high-energy acoustic modes that travel coherently within the dot. As the dot size increases, an energy dissipation toward low-energy phonons takes place, and the transport becomes diffusive. Because ultrafast diffraction provides the atomic-scale resolution and a sufficiently high time resolution, other nanostructured materials can be studied similarly to elucidate the nature of dynamical energy localization.
Vanacore, G., Hu, J., Liang, W., Bietti, S., Sanguinetti, S., & Zewail, A. (2014). Diffraction of Quantum Dots Reveals Nanoscale Ultrafast Energy Localization. NANO LETTERS, 14(11), 6148-6154.
Citazione: | Vanacore, G., Hu, J., Liang, W., Bietti, S., Sanguinetti, S., & Zewail, A. (2014). Diffraction of Quantum Dots Reveals Nanoscale Ultrafast Energy Localization. NANO LETTERS, 14(11), 6148-6154. |
Tipo: | Articolo in rivista - Articolo scientifico |
Carattere della pubblicazione: | Scientifica |
Presenza di un coautore afferente ad Istituzioni straniere: | Si |
Titolo: | Diffraction of Quantum Dots Reveals Nanoscale Ultrafast Energy Localization |
Autori: | Vanacore, G; Hu, J; Liang, W; Bietti, S; Sanguinetti, S; Zewail, A |
Autori: | |
Data di pubblicazione: | 2014 |
Lingua: | English |
Rivista: | NANO LETTERS |
Digital Object Identifier (DOI): | http://dx.doi.org/10.1021/nl502293a |
Appare nelle tipologie: | 01 - Articolo su rivista |