Westfälische Wilhelms-Universität Münster
- Fachbereich Physik -
KOLLOQUIUM ÜBER SPEZIELLE FRAGEN DER PHYSIK
Montag, 23. Juni 1997
Prof. Dr. J. Zi
Fudan University, Shanghai
Theory of Raman scattering from optical and
acoustic phonons in Si nanocrystals
Si nanostructures including porous Si and nanocrystals have received
considerable attention since the discovery of room-temperature light-emitting
from these systems. We have known well about the scattering from phonons
in bulk, quantum-wells, or superlattices. But for the zero-dimensional
nanocrystals it is not the same case. We know little about the behaviour
of phonons in nanocrystals and there are only few microscopic calculations
of phonons. In our work we use the force-constants as obtained by the method
proposed by Falter et al. as input and construct the dynamical matrix.
The confinement of optical phonons is discussed and a relation between
the Raman frequency and the size is established. Only the LO phonons contribute
to the Raman scattering in the usual back-scattering and off-resonant condition.
We also study the Raman scattering from the acoustic phonons. Both LA-
and TA-like phonons contribute to the scattering.
Ort: Wilhelm-Klemm-Str. 9, Hörsaal 404
Zeit: 17 Uhr c.t.
Einladender: Falter