Carbon Allotrope Dependence on Temperature and Pressure During Thermal Decomposition of Silicon Carbide
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thesis / dissertation description
Bulk CNT and graphene films form on SiC using a metal-catalyst-free thermal decomposition approach. In this work, the background vacuum pressure and temperature used in the decomposition process are varied to investigate their impact on the type and quality of carbon allotrope formed on the SiC substrate. The carbon nanostructure growth is performed using two approaches, both of which involve intense heating (1400-1700 deg C) of SiC under moderate vacuum conditions (0.01 - 0.00001 Torr). The first growth method uses a conventional graphite resistance furnace capable of annealing waferscale samples over 1700 deg C under vacuum. Using this approach, post-growth characterization is performed using both SEM and Raman spectroscopy. The second growth approach heats an illuminated area of the SiC substrate under vacuum conditions, resulting in a micro-meter scale growth process. Unique to this micro-scale approach is that in-situ Raman spectroscopy is performed yielding instantaneous characterization of the resultant carbon nanostructure. This work focuses on using the laser-induced growth technique to refine ideal growth parameters of bulk nanostructure films. This work reports results and findings for various parameter sets implemented during growth, providing insight into the physical mechanism of the growth process.