Size-independent low-frequency Raman scattering in Ge-nanocrystal-embedded SiO2 films.
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.
Liu
L Z
LZ
Nanjing National Laboratory of Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China.
Wu
X L
XL
Gao
F
F
Yang
Y M
YM
Li
T H
TH
Chu
Paul K
PK