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Ultrafast acoustic phonon ballistics in semiconductor heterostructures

Ultraschnelle akustische Phononenballistik in Halbleiter-Heterostrukturen
: Baumberg, J.J.; Williams, D.A.; Köhler, K.


Physical review letters 78 (1997), Nr.17, S.3358-3361 : Ill.
ISSN: 0031-9007
Fraunhofer IAF ()
III-V Halbleiter; III-V semiconductors; quantum wells; time resolved photoluminescence; zeitaufgelöste Photolumineszenz

Using a two-color ultrafast surface deflection spectroscopy, we demonstrate the time-resolved observation of acoustic phonon wave packets emitted from a single buried GaAs quantum well. A longitudinal acoustic phonon pulse is generated at a preselected depth within a highly confined region (>=10 nm thick) through the coherent nonequilibrium deforation potential which was previously unobserved in such structures. Subsequent detection with subpicosecond resolution at the surface resolves propagating high-wave-vector ballistic phonons and quasiballistic or "snake" phonons which subsequently merge into a quasidiffusive phonon pulse.