Vibrational modes in amorphous silicon dioxide
2000; Elsevier BV; Volume: 292; Issue: 3-4 Linguagem: Inglês
10.1016/s0921-4526(00)00475-0
ISSN1873-2135
Autores Tópico(s)Thin-Film Transistor Technologies
ResumoThe optical properties of the broad absorption region due to asymmetric stretching vibration of bridging oxygen in the amorphous structure of bulk SiO2 were studied. The complex refractive index of thick densified chemical-vapour-deposited silicon oxide film was calculated and used further to obtain the dielectric response function of the sample. Vibrational modes were analysed by energy-loss functions for transverse and longitudinal optical phonons. In the 900–1300 cm−1 spectral region, three vibrational modes with well-resolved TO–LO phonon splitting were obtained. The phonon spectra appears as the smeared-out version of the crystalline counterpart, i.e. the α-quartz. The most intense phonon couple at 1064 (TO), and 1248 cm−1 (LO) has the smallest damping and appears to be more crystalline-like than the remaining two. The broad frequency distribution of lattice-like phonon lines gives rise to frequency-dependent damping where the phonons only purely feel each other and have different phonon decays.
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