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Proceedings Paper

Cerenkov generation of confined acoustic and optical phonons in quantum wells
Author(s): Ki Wook Kim; Sergiy Mikhailovich Komirenko; Viatcheslav A. Kochelap; Michael A. Stroscio
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Paper Abstract

It is well known for bulk semiconductors that amplification (generation) of a phonon mode can be achieved via the Cerenkov effect when the electron drift velocity exceeds the phonon phase velocity. The following three requirements are necessary for practical use of this effect: high electron mobilities, large electron densities, and strong coupling between electrons and phonons. In this report we show that in quantum well heterostructures these requirements can be met and both confined acoustic and confined optical phonon modes can be efficiently generated (amplified) by the drift of two-dimensional carriers. General formulae for the gain coefficient as a function of the acoustic phonon frequency and structure parameters as well as for the confined phonon increment are derived. Taking into account the electron-acoustic-phonon interaction through the deformation potential as well as the piezoelectric interaction, we found that amplification coefficient can reach hundreds of 1/cm for the AlGaAs-based heterostructures and thousands of 1/cm for the SiGe-based heterostructures in the terahertz phonon frequency range. Amplification takes place in a spectrally separated and relatively narrow amplification bands. We show that the optical phonon increment depends critically on the electron drift velocity. Detailed analysis of the optical phonon increment as a function of phonon wavevector, electron-phonon coupling strength, electron temperature and drift velocity indicates that the electron drift in selectively doped AlAs/GaAs/AlAs and GaSb/InSb/GaAs quantum wells can generate coherent confined optical modes. Finally, we discuss nonlinear mechanisms which stabilize the increase of phonon population and lead to the steady state phonon generation.

Paper Details

Date Published: 11 June 2002
PDF: 15 pages
Proc. SPIE 4643, Ultrafast Phenomena in Semiconductors VI, (11 June 2002); doi: 10.1117/12.470408
Show Author Affiliations
Ki Wook Kim, North Carolina State Univ. (United States)
Sergiy Mikhailovich Komirenko, North Carolina State Univ. (United States)
Viatcheslav A. Kochelap, Institute of Semiconductor Physics (Ukraine)
Michael A. Stroscio, Univ. of Illinois/Chicago (United States)

Published in SPIE Proceedings Vol. 4643:
Ultrafast Phenomena in Semiconductors VI
Kong-Thon F. Tsen; Jin-Joo Song; Hongxing Jiang, Editor(s)

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