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