Raman Spectroscopy of Oxide-Embedded and Ligand-Stabilized Silicon Nanocrystals.
Oxide-embedded and oxide-free alkyl-terminated silicon (Si) nanocrystals with diameters ranging from 3 nm to greater than 10 nm were studied by Raman spectroscopy. For ligand-passivated nanocrystals, the zone center Raman-active mode of diamond cubic Si shifted to lower frequency with decreasing size, accompanied by asymmetric peak broadening, as extensively reported in the literature. The size dependence of the Raman peak shifts, however, was significantly more pronounced than previously reported or predicted by the RWL (Richter, Wang, and Ley) and bond polarizability models. In contrast, Raman peak shifts for oxide-embedded nanocrystals were significantly less pronounced as a result of the stress induced by the matrix.
Colin M
CM
Hessel
Junwei
J
Wei
Dariya
D
Reid
§Department of Electrical Engineering and Information Systems, School of Engineering, The University of Tokyo, Tokyo, Japan.
Hiromasa
H
Fujii
Michael C
MC
Downer
Brian A
BA
Korgel
BP model; HSQ; RWL model; Raman spectroscopy; SAXS; TEM; X-ray diffraction; XRD; amorphous silicon; hydrogen silsesquioxane; modeling; oxide-embedded; phonon confinement; silicon nanocrystals; size determination; small-angle X-ray scattering; transmission electron microscopy