Abstract
In this talk, I would like to discuss the optical properties of multilayer epitaxialgraphene at low and high energies (1.5 – 35 eV). Multilayer epitaxial graphenegrown by thermal decomposition on the carbon face (MEG-C) of a SiC
substrates exhibit the electronic and optical properties of freestanding
graphene, in which the interaction between graphene and underlying
substrate is absent. This is due to the existence of different orientations
between adjacent graphene layers which decouples those graphene layers.
On the one hand, the low energy optical properties of MEG-C resemble to that
of chemical vapour deposition (CVD) graphene on SiO2 substrate where one
can observe universal optical conductivity below 2 eV and asymmetric
absorption peak at 4.5 eV due to the process of interband transition and the
interaction between the electrons and electron-hole at M-points in the Brillouin
zone of graphene [1-4]. On the other hand, the high energy optical properties
of MEG-C has not been studied in details. According to the theory based on
density functional calculation (DFT) with local density approximation (LDA) in
which GW many-body effect and electron-hole interaction were included, the
absorption peak of freestanding graphene and bilayer graphene should occur
at 11 eV and 14.5 eV due to the uniqueness of parallel band between σ and
π* band [5]. I will report our recent optical data of MEG-C taken at very broad
energy range and will discuss the optical constant related to the dynamics of
the electrons of freestanding graphene at high energy