We investigate disordered graphene with strong long-range impurities. Contrary to the common belief that delocalization should persist in such a system against any disorder, as the system is expected to be equivalent to a disordered two-dimensional Dirac fermionic system, we find that states near the Dirac points are localized for sufficiently strong disorder (therefore inevitable intervalley s...

In this paper, we report a study of graphene and graphene field effect devices after their exposure to a series of short pulses of oxygen plasma. Our data from Raman spectroscopy, back-gated field-effect and magnetotransport measurements are presented. The intensity ratio between Raman ‘D’ and ‘G’ peaks, ID/IG (commonly used to characterize disorder in graphene), is observed to initially increa...

Current etching routes to process large graphene sheets into nanoscale graphene so as to open up a bandgap tend to produce structures with rough and disordered edges. This leads to detrimental electron scattering and reduces carrier mobility. In this work, we present a novel yet simple direct-growth strategy to yield graphene nanomesh (GNM) on a patterned Cu foil via nanosphere lithography. Ram...

Graphene is a new material whose unique electronic structure endows it with many unusual properties [1]. A monolayer graphene is a gapless two-dimensional (2D) semiconductor with a massless electron-hole symmetric spectrum near the corners of the Brillouin zone, ǫ(k) = ±~v|k|, where v ≈ 10 cm/s. The concentration of these “Dirac” quasiparticles can be accurately controlled by the electric field...

We calculate the average single-particle density of states in graphene with disorder due to impurity potentials. For unscreened short-ranged impurities, we use the non-self-consistent and self-consistent Born and T-matrix approximations to obtain the self-energy. Among these, only the self-consistent T-matrix approximation gives a nonzero density of states at the Dirac point. The density of sta...

Employing the kernel polynomial method (KPM), we study the electronic properties of the graphene bilayers with Bernal stacking in the presence of diagonal disorder, within the tight-binding approximation and nearest neighbor interactions. The KPM method enables us to calculate local density of states (LDOS) without the need to exactly diagonalize the Hamiltonian. We use the geometrical averagin...