| Since graphene was first isolated using adhesive tape in 2004, it has become a rising star of condensed matter physics, material science and attracted great attentions from physicists and material engineers due to its unique properties such as massless Dirac fermions, high electron mobility and anomalous quantum Hall effect. The Nobel Prize in Physics for 2010 was awarded to Andre Geim and Konstantin Novoselov "for groundbreaking experiments regarding the two-dimensional material graphene". This dissertation summaries my efforts on first-principles studies of the electronic properties of epitaxial graphene from five topics.;The first system investigated is the graphene on carbon face 6H-SiC substrate. By introducing dispersion forces into calculations, the electronic band structure shows n type doped graphene behavior which corrects previous neutral results in literature. Besides 6H-SiC which has been extensively studied, for the first time we have successfully simulated graphene on 3C-SiC(100) and Si(111)-7x7 substrates which are relatively new approaches of fabrication and have advantages on applications. Our results have confirmed the linear dispersion near Dirac point for both cases. As water is always present in the environment of graphene based electronic devices, the influences of water on epitaxial graphene are investigated, where Dirac point shift is observed. As last part of the dissertation, the phonons and Raman scattering of epitaxial graphene on silicon face 6H-SiC and freestanding graphene under uniaxial strain are discussed. |
