With a home-made chemical vapor deposition (CVD) system, we have successfully prepared large-scaled (up to several centimeters) graphene on transition metals. The produced graphene were then transferred onto arbitrary substrates like SiO2/Si wafer, and Raman spectroscopy was used for charactering the layer number and film quality. By controlling the growth conditions, such as pressure, temperature and gas compositions, monolayer-dominant graphene with different degree of structural disorder can be obtained. 

The Raman spectra showed the typical profiles of graphene with different D to G peak ratio, which can be used for estimation of defect density by reported formula. We found that the calculated defect density is corresponding to the carrier mobility. The carrier mobility was obtained by Hall measurement based on Van der pauw method.

Further analyses using Raman spectroscopy on the disorder effecting are under processing. 

J.-Y. Hwang, C.-C. Kuo, L.-C. Chen and K. H. Chen, Correlating Defect Density with Carrier Mobility in Large-Scaled Graphene Films: Raman Spectral Signatures for Estimation of Defect Density, Nanotechnology, 2010, 21, 465705

C.-K. Chang^#; J. Y. Hwang^#; W. J. Lai; C. W. Chen; C. I. Huang; K. H. Chen; L. C. Chen, Influence of Solvent on the Dispersion of Single-Walled Carbon Nanotubes in Polymer Matrix and the Photovoltaic Performance, Journal of Physical Chemistry C, 2010, 114, 10932

J. Y. Hwang; A. Chartterjee; C. H. Shen; J. H. Wang; C. L. Sun; O. Chyan; C. W. Chen; K. H. Chen; L. C. Chen; Mesoporous Activated Carbon Dispersed with Ultra-fine Platinum Nanoparticles and their Electrochemical Properties, Diamond Related Materials, 2009, 18, 303

J. Y. Hwang; A. Nish; J. Doig; S. Douven; C. W. Chen; L. C. Chen; R. J. Nicholas, Polymer Structure and Solvent Effects on the Selective Dispersion of Single-Walled Carbon Nanotubes, Journal of American Chemical Society, 2008, 130, 3543

A. Nish; J. Y. Hwang; J. Doig; R. J. Nicholas, Highly Selective Dispersion of Single-Walled Carbon Nanotubes using Aromatic Polymers, Nature Nanotechology, 2007, 2, 640

Invited talk in Department of Physics, National Cheng Kung University, Taiwan, 2010/10

Award of postdoctoral-fellowship of National Science Council, 2010/07 (project: Growth and characterization of chemical vapor deposition-grow graphene)

Poster-award in conference of New Diamond and Nano Carbons (NDNC), 2008

Award of project of thousand mile horse for doing research in Department of Physics, University of Oxford, U.K., 2006/06 – 2007/05