High-resolution analogue of time-domain phonon spectroscopy in the transmission electron microscope.

ABSTRACT: Femtosecond photoexcitation of semiconducting materials leads to the generation of coherent acoustic phonons (CAPs), the behaviours of which are linked to intrinsic and engineered electronic, optical and structural properties. While often studied with pump-probe spectroscopic techniques, the influence of nanoscale structure and morphology on CAP dynamics can be challenging to resolve with these all-optical methods. Here, we used ultrafast electron microscopy (UEM) to resolve variations in CAP dynamics caused by differences in the degree of crystallinity in as-prepared and annealed GaAs lamellae. Following in situ femtosecond photoexcitation, we directly imaged the generation and propagation dynamics of hypersonic CAPs in a mostly amorphous and, following an in situ phototherm

SUBMITTER: VandenBussche EJ 

PROVIDER: S-EPMC7661281 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature