title: Size-independent low-frequency Raman scattering in Ge-nanocrystal-embedded SiO2 films.
abstract: The peak position and linewidth of the low-frequency Raman mode observed from amorphous silica films embedded with Ge nanocrystals doped with Si show a size-independent behavior. Spectral analysis reveals the formation of a thin amorphous GeSi layer on the surface of the Ge nanocrystal. Theoretical calculation based on a modified three-region model discloses that the acoustic impedance of the interfacial GeSiO layer is responsible for the size-independent behavior. During high-temperature annealing, Ge atoms are segregated from the interface into the core, and the GeSiO interface layer is converted to SiO(2), leading to disappearance of the size-independent vibration mode.
authors.affiliation: Nanjing National Laboratory of Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China.
authors.forename: L Z
authors.initials: LZ
authors.lastname: Liu
authors.forename: X L
authors.initials: XL
authors.lastname: Wu
authors.forename: F
authors.initials: F
authors.lastname: Gao
authors.forename: Y M
authors.initials: YM
authors.lastname: Yang
authors.forename: T H
authors.initials: TH
authors.lastname: Li
authors.forename: Paul K
authors.initials: PK
authors.lastname: Chu