Low‐Frequency Raman Scattering from Nanocrystals Caused by Coherent Excitation of Phonons

Ultrahigh-resolution transmission electron microscopy clearly reveals the absence of a disordered or softer interface layer between GexSi1–x nanocrystals (NCs) and the SiO2 matrix. A theory shows that the collective modes comprising coherent excitation of phonons in a large number of NCs contribute to the Raman scattering. This work provides a new understanding of low-frequency Raman scattering from NC-embedded matrices.