Generation and propagation of a picosecond acoustic pulse at a buried interface: time-resolved x-ray diffraction measurements.
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.
Lee
S H
SH
FOCUS Center and Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040, USA. shl@umich.edu
Cavalieri
A L
AL
Fritz
D M
DM
Swan
M C
MC
Hegde
R S
RS
Reason
M
M
Goldman
R S
RS
Reis
D A
DA