Synthesis and characterization of low dimensional carbon materials.
Date of Issue2011
School of Physical and Mathematical Sciences
This thesis presents the research works on synthesis and characterization of low dimensional carbon materials, including single-walled carbon nanotubes (SWNTs), sp hybridized carbon chain (Cn) and SWNT hybrid system, single layer graphene, bilayer graphene, nitrogen doped graphene, and hydrogenated graphene. Synthesis of high quality vertically aligned SWNTs by plasma enhanced chemical vapor deposition was achieved at low temperature (500 oC). For low temperature synthesis of SWNTs, both aggressive ion bombardment in discharge sheath and large C2H4/H2 flow rate ratio can lead a structural transition from SWNTs to few-walled carbon nanotubes. In capactively coupled radio frequency plasma, the ion flux, which is significantly dependent on the plasma powers and pressures, was found to be the determinant factor of the ion bombardment etching effect. With low density radio frequency plasma and special Co-Fe catalyst, linear carbon chains encapsulated in SWNTs, Cn@SWNTs, were synthesized for the first time. The sp hybridized linear carbon chains were identified by resonant Raman spectroscopy and high resolution transmission electron microscopy. The charge transfer between carbon chains and SWNT make this unique hybrid system a novel one dimensional metal with Luttinger-liquid behavior. Single layer graphene and bilayer graphene were synthesized homogeneously in a controllable manner by low pressure chemical vapor deposition. The electronic structures of bilayer graphene were characterized by Raman spectroscopy, photoelectron spectroscopy and optical absorption spectroscopy, and carrier dynamics in bilayer graphene was probed by transient absorption spectroscopy.