Raman Study of Silicon Small Particles

The particle-size dependence of Raman spectra of gas-evaporated silicon small particles, whose size distribution is well described by a log-normal distribution function, is reported in connection with their electron diffraction patterns. Although a diamond structure is confirmed by the Debye-Scherrer rings for the samples with an average particle size from 70 to 220 Å, the Raman spectra are rather complex; the spectra are resolved into a new surface mode and three known modes (LA, TO and allowed-TO ones) in a range of 250 to 600 cm -1 . A disadvantage of the present theoretical studies relating to the finite-size effects of microcrystalline silicon is pointed out.