Effect of substrate to filament distance on formation and photoluminescence properties of indium catalyzed silicon nanowires using hot-wire chemical vapor deposition

Si nanowires have been synthesized by hot-wire chemical vapor deposition technique, with Indium nanocones employed as catalysts with different substrate to filament distances ranging from 6 to 3 cm. Reducing the substrate to filament distance resulted in the retention of more atomic H radicals on the growth sites. The atomic H radicals acted to induce the catalytic growth and enhance the crystallinity of the Si nanowires. The Si nanowires showed tapering structures due to the radial growth of columnar Si nanocrystallites on the middle and base walls of the nanowires. The oxide-related defects on the outer layer of the Indium nanocones and Si nanowires, as well as the Si nanocrystallites on walls of the Si nanowires, contributed to the visible orange and red photoluminescence.

► Reduction of substrate to filament distance retained more H atoms on the growth sites. ► H atoms played a main role on inducing the catalytic growth of Si nanowires from In. ► Crystallinity of Si nanowires was enhanced due to the increase of H etching effect. ► Photoluminescence (PL) at 620 nm related to oxide defects in In and Si structures. ► Si nanocrystalline columns on walls of the nanowires contributed the PL at 700 nm.