Using sound to generate ultra-high-frequency electron dynamics in superlattices
✍ Scribed by M.T. Greenaway; A.G. Balanov; D. Fowler; A.J. Kent; T.M. Fromhold
- Publisher
- Elsevier Science
- Year
- 2009
- Tongue
- English
- Weight
- 427 KB
- Volume
- 40
- Category
- Article
- ISSN
- 0026-2692
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✦ Synopsis
We show that a phonon wave propagating through a semiconductor superlattice can induce a charge current even when no static electric field is applied. When the energy amplitude of the phonon wave is less than the width of the lowest superlattice miniband, we find strong resonant enhancement of electron transport, accompanied by very high frequency oscillations of the electron orbits. In this regime, the phonon wave drags the electrons through the superlattice, causing them to undergo quasiperiodic trajectories with a single dominant temporal frequency several orders of magnitude higher than that of the phonon deformation wave itself. This transformation of GHz frequency wave motion into highly coherent THz frequency electron dynamics provides a mechanism for frequency upconversion, with a multiplication factor of % 20 in our present samples. For phonon wave amplitudes higher than the miniband width, the electrons perform Bloch-like oscillations, which dramatically suppresses transport.