The effect of Si-nanocrystal (Si-nc) size distribution on Raman spectrum is studied in detail within the framework of a phonon confinement model. It is found that size distribution has little effect on Raman frequency shift, but greatly affects the width and shape of Raman spectrum. Si-nc Raman spectrum can be well explained by considering the size distribution. Furthermore, a set of simple relationships between Raman frequency shift/full width at half maximum (FWHM) and size distribution is set up based on the framework of a modified phonon confinement model, which can be applied to calculate Si-nc size distribution from the Raman spectrum.

We report Raman scattering and field emission properties of rutile RuO2 nanorods obtained by metalorganic chemical vapor deposition. The RuO2 nanorods have lengths up to several micrometers and diameters in the range of 10–50 nm. The nanosize dependencies of the peak shift and the broadening of the three first-order Raman modes agree well with those calculated on the basis of the phonon confinement model. The unique geometrical features of RuO2 nanorods exhibit a strong effect on field enhancement (β∼1153), which results in a low threshold field (Eth∼4.9V∕μm) defined at the beginning of emission. The low turn-on field for driving a current of 10μA∕cm2 is about 10.3V∕μm, which is comparable with amorphous carbon film. Our results indicate that RuO2 nanorods provide an excellent alternative for field emitter due to several advantages, including nanometer structure, natural conductor, enhanced resistance to oxidation, and long-term stability.

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