We report on the optical generation and detection of ultrashort acoustic pulses that propagate in three-dimensional semiconductor crystals. Photoexcitaiton of lattice-matched GaP layers grown on Si(001) gives rise to a sharp spike in transient reflectivity due to the acoustic pulse generated at the GaP/Si interface and detected at the GaP surface and vice versa. The extremely short width of the reflectivity spike, 0.5 ps, would translate to a spatial extent of 3 nm or 10 atomic bilayers, which is comparable with the width of the intermixing layer at the GaP/Si interface. The reflectivity signals are also modified by quasi-periodic Brillouin oscillations of GaP and Si arising from the acoustic pulses during the propagation in the crystals. The present results demonstrate the potential application of the simple optical pump-probe scheme in the nondestructive evaluation of the buried semiconductor interface quality.
@article{arxiv.1612.01239,
title = {Sub-picosecond acoustic pulses at buried GaP/Si interfaces},
author = {Kunie Ishioka and Avinash Rustagi and Andreas Beyer and Wolfgang Stolz and Kerstin Volz and Ulrich Hoefer and Hrvoje Petek and Christopher J. Stanton},
journal= {arXiv preprint arXiv:1612.01239},
year = {2017}
}