Dual catalytic purpose of the tungsten filament during the synthesis of single-helix carbon microcoils by hot-wire CVD.

We report on the deposition of crystalline single-helix carbon microcoils, in the as-deposited state, by the hot-wire chemical vapor deposition process without any special preparation of nano-sized transition metal catalysts and subsequent post-deposition annealing. Tungsten, originating from the heated tungsten filament, is identified as the catalyst material responsible for the growth of the microcoils. High-resolution transmission spectroscopy, combined with Raman spectroscopy, confirm that the as-deposited microcoils are crystalline, which is induced by the high deposition temperature in the vicinity of the heated filament.

Thermally Induced Nano-Structural and Optical Changes of nc-Si:H Deposited by Hot-Wire CVD.

We report on the thermally induced changes of the nano-structural and optical properties of hydrogenated nanocrystalline silicon in the temperature range 200-700 degrees C. The as-deposited sample has a high crystalline volume fraction of 53% with an average crystallite size of ~3.9 nm, where 66% of the total hydrogen is bonded as identical withSi-H monohydrides on the nano-crystallite surface.

Effect of deposition pressure on the morphology and structural properties of carbon nanotubes synthesized by hot-filament chemical vapor deposition.

Hot-filament chemical vapor deposition has developed into an attractive method for the synthesis of various carbon nanostructures, including carbon nanotubes. This is primarily due to its versatility, low cost, repeatability, up-scalability, and ease of production. The resulting nano-material synthesized by this technique is dependent on the deposition conditions which can be easily controlled.