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HL: Fachverband Halbleiterphysik
HL 69: Quantum dots and wires III
HL 69.4: Vortrag
Donnerstag, 19. März 2020, 16:00–16:15, POT 151
Polar optical phonons’ splitting in nanowires — •Norma Rivano1, Thibault Sohier1,2, and Nicola Marzari1 — 1Theory and Simulation of Materials (THEOS) and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland — 2nanomat/QMAT/CESAM and European Theoretical Spectroscopy Facility, Université de Liège, Belgium
The need for an accurate description of the vibrational properties of 1D materials is strongly motivated by the growing interest in low-dimensionality in general and semiconductor nanowires in particular. Dimensionality has been shown to have an important impact on materials’ properties, thus being crucial for both fundamental understanding and technological applications. At small momenta, longitudinal and transverse polar-optical modes are known to undergo a frequency splitting which depends upon the phonon wave-vector, the effective charges, the dielectric properties and the dimensionality of the system. Indeed, in the long-wavelength limit, the amount of electrostatic energy built up by the longitudinal polar-optical phonons is finite in 3D, but it vanishes in 2D. Here, we show that it also vanishes in 1D, but with a different asymptotic behavior. We also discuss the role of the nanowire’s radius, which is particularly relevant for characterization through Raman spectroscopy. To this aim, we develop an analytical model and compare it with ab-initio simulations. We provide insights into the vibrational physics of nanowires as well as a ready-to-use tool for the experimental community to encourage further studies.