Silicon Carbide Nanosprings

Abstract

Amorphous silicon carbide nanosprings, as well as biphase (crystalline core/amorphous sheath) helical nanowires, have been synthesized by plasma enhanced chemical vapor deposition. Both variants grow via the vapor−liquid−solid mechanism. The formation of the amorphous silicon carbide nanosprings is explained in terms of the contact angle anisotropy model initially proposed to explain the formation of amorphous boron carbide nanosprings. A modified contact angle anisotropy model, where the presence of temperature gradients within the catalyst are imposed, has been proposed to explain the formation of the biphase helical nanowires. The basis for this model is that the crystalline core acts to pin the catalyst, thereby prohibiting nanospring formation. The model is supported by the experimental observation of a transition to nanospring growth at the point of extinction of the crystalline core of a linear biphase nanowire at a position where the catalyst is off-center with respect to the axis of the growth direction.