Study the effect of plasma power density and gold catalyst thickness on Silicon Nanowires growth by Plasma Enhanced Chemical Vapour Deposition

Gold (Au) metal catalysed tapered Silicon Nanowires (SiNWs) of diameter 50-150 nm at the base and length of 0.8-2.5 µm are synthesised by VLS mechanism using Silane (SiH4) as a precursor gas in Plasma Enhanced Chemical Vapour Deposition (PECVD) reactor at a substrate temperature of 650 °C. In this work, the effect of plasma power on the growth morphology of SiNWs is studied with two different thicknesses of Au catalyst layer. The catalyst layers are deposited using thermal evaporation system. Field Emission Scanning Electron Microscopy (FESEM) images confirm the growth of randomly oriented tapered nanowires. From the FESEM studies, it is clear that the density and the length of SiNWs increases with the increase of plasma power. High-resolution Transmission Electron Microscopy (HRTEM) demonstrated that the SiNWs are highly crystalline with (1 1 1) and (2 2 0) plane orientation. Raman spectra of SiNWs have been analysed and the first order optical phonons for SiNWs is observed at 519 cm−1 with 1 nm and 514.82 cm−1 with 2 nm Au catalyst.