Silicon/silicon carbide (Si/SiC) core-shell nanowires grown on quartz substrates by hot-wire chemical vapor deposition were studied. Nickel was used as a catalyst to induce the growth of these core-shell nanowires followed by the vapor-solid-solid growth mechanism. The nanowires were grown by varying substrate-to-filament distance; d(s-f) from 1.9 to 3.1 cm with an interval of 0.4 cm. Lower d(s-f) produced a high density of straight core-shell nanowires. A highly crystalline single crystal Si core of the nanowires was produced at lower d(s-f) as well. Presence of Si and SiC nano-crystallites embedded within an amorphous matrix in the shell of the nanowires exhibited a high intensity of photoluminescence emission spectra from 600 to 1000 nm. The effects of the d(s-f) on the structural and optical properties of the nanowires are discussed. (C) 2014 Elsevier B.V. All rights reserved.