Raman analysis of oxide cladded silicon core nanowires grown with solid silicon feed stock

Solid–liquid–solid (SLS) combined with Vapor-liquid–solid (VLS) growth mechanism has been used for synthesizing Core-clad silicon nanowires (SiNWs) by thermal annealing onto two different catalyst substrates (Au/Si and Ni/Ti/Si). It provides a novel method to synthesize SiNWs which is cost-effective, large-area-compatible and may give a higher degree of control of the end product, facilitated by the simple experimental process for further device applications. The first-order Raman peaks of the SiNWs were found to shift and to broaden asymmetrically in comparison to the c-Si Raman peak. Using a phonon confinement model, the average diameter of the wires can be estimated from the Raman spectra but are consistently lower than the diameters measured using high-resolution transmission electron microscopy. We interpret this as due to the confining contribution of the oxide clad. Due to the simplicity of the method, it could be adapted in industry for large scale synthesis of SiNWs with oxide clad for device fabrication, e.g., surround-gate field effect transistors.