Synthesis and optical properties of silicon nanowires grown by different methods

We review our recent results on the growth and characterization of silicon nanowires (SiNWs). Vapour-phase deposition techniques are considered, including chemical vapour deposition (CVD), plasma-enhanced chemical vapour deposition (PECVD), high-temperature annealing, and thermal evaporation. We present complementary approaches to SiNW production. We investigate the low-temperature (down to 300 degrees C) selective nucleation of SiNWs by Au-catalysed CVD and PECVD. Bulk production of SiNWs is obtained by thermal-vapour deposition from Si/SiO powders in a high-temperature furnace. In this case, SiNWs grow either by condensing on Au catalyst films, or by self-condensation of the vapour in a lower-temperature region of the furnace. Finally, we also achieve controlled growth by thermolysis of nanopatterned, multi-layered Si/Au thin-film precursors. The as-produced wires are compared in terms of yield, structural quality, and optical properties. Raman and photoluminescence spectra of SiNWs are discussed.