title: Generation and propagation of a picosecond acoustic pulse at a buried interface: time-resolved x-ray diffraction measurements.
abstract: We report on the propagation of coherent acoustic wave packets in (001) surface oriented Al0.3Ga0.7As/GaAs heterostructure, generated through localized femtosecond photoexcitation of the GaAs. Transient structural changes in both the substrate and film are measured with picosecond time-resolved x-ray diffraction. The data indicate an elastic response consisting of unipolar compression pulses of a few hundred picosecond duration traveling along [001] and [001] directions that are produced by predominately impulsive stress. The transmission and reflection of the strain pulses are in agreement with an acoustic mismatch model of the heterostructure and free-space interfaces.
authors.affiliation: FOCUS Center and Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040, USA. shl@umich.edu
authors.forename: S H
authors.initials: SH
authors.lastname: Lee
authors.forename: A L
authors.initials: AL
authors.lastname: Cavalieri
authors.forename: D M
authors.initials: DM
authors.lastname: Fritz
authors.forename: M C
authors.initials: MC
authors.lastname: Swan
authors.forename: R S
authors.initials: RS
authors.lastname: Hegde
authors.forename: M
authors.initials: M
authors.lastname: Reason
authors.forename: R S
authors.initials: RS
authors.lastname: Goldman
authors.forename: D A
authors.initials: DA
authors.lastname: Reis