(571b) Synthesis and Raman Spectroscopy of Sic Nanowires

Silicon carbide nanowires have attractive applications as components of nano-electromechanical sensors and nano-optical circuits able to function in harsh environment. Notorious challenges accompany the production of high quality SiC (twin boundaries, micropipes, dislocations, and inclusions) preventing it from attaining widespread use for macro/nano devices. Therefore, the synthesis of highly crystalline SiC nanowires and the development of quantitative, nondestructive approaches to screen individual nanowires for chemical and structural properties have a potentially big technological impact.

SiC nanowires were synthesized in a cold wall LPCVD reactor using a single precursor. It was observed that growth using a nickel catalyst results in nanowires with a higher level of crystallinity than with a platinum or gold catalyst, as characterized by electron microscopy and Raman spectroscopy. Confocal Raman spectroscopy permits the direct characterization of the nature of bulk and surface defects, such as the presence of a carbon shell in some specimens, of carbon inclusions in others, and of divancancies in all. This work establishes the potential of polarized confocal Raman mapping as a technologically important alternative to the more difficult and costlier and usually destructive measurements involving electron microscopy or nanomechanical probes for rapid batch testing of nanowire properties and nondestructive screening of nanowire-based devices.