Raman spectral study of silicon nanowires

Raman spectra of silicon nanowires (Si NW's) have been analyzed, and the ob served Raman peaks were assigned. The typical features of the first-order R aman peaks of the optical phonons were found matching those predicted by th e quantum confinement effect. However, the sizes of Si NW's, derived from t he microcrystal model (MCM) of Raman spectra do not fit the usual confined size, the diameter, of the nanowires from transmission electron microscope images. Abundant structure defects can be observed in Si NW's so that the S i NW's actually consist of many smaller Si grains. The size of such Si grai ns was found to give a better agreement with the size derived from the Rama n spectra. This indicates that MCM can be used to interpret the Raman spect rum of Si NW's as long as one takes into account the influence of defect on the confined size. [S0163-1829(99)01303-X].