Modification of the phonon spectrum of bulk Si through surface nanostructuring

Abdo Iskandar (1, 2) , Agnieszka Gwiazda (2) , Yi Huang (2) , Michel Kazan (1) , Aurélien Bruyant (2) , Malek Tabbal (1) , Gilles Lerondel (2)

1 AUB - American University of Beirut [Beyrouth]
2 LNIO - Laboratoire de Nanotechnologie et d'Instrumentation Optique

n this paper, we present experimental evidence on the change of the phonon spectrum and vibrational properties of a bulk material through phonon hybridization mechanisms. The phonon spectrum in a finite material is strongly affected by the presence of free surfaces, which is the addition of a contribution from an essentially two-dimensional crystal. The phonon spectrum of a bulk material can hence be altered by a hybridization mechanism between confined phonon modes in nanostructures introduced on the surface of a bulk material and the underlying bulk phonon modes. We measured the heat capacities of bare and surface-structured silicon substrates originating from the same silicon wafer. Then, we deduced important features of the phonon spectra of the samples investigated through a rigorous analysis of the measured heat capacity curves. The results show that the shape and size of the nanostructures made on the surface of the bulk substrate have a strong effect on the phonon spectrum of the bulk material.

Keywords: Lattice dynamics; Electron gas; Dispersion function; Debye temperature; Semiconductor device fabrication; Vibrational properties; First-principle calculations; Phonons; Semiconductor materials; Thermodynamic properties

Domains: Micro and nanotechnologies/Microelectronics; Materials Science [cond-mat.mtrl-sci]

Abdo Iskandar, Agnieszka Gwiazda, Yi Huang, Michel Kazan, Aurélien Bruyant, et al.. Modification of the phonon spectrum of bulk Si through surface nanostructuring. E-MRS 2017 spring Meeting, Nanomaterial symposium U, May 2017, Strasbourg, France. ⟨hal-02525674⟩