Structural analysis of multilayer graphene via atomic moiré interferometry

Abstract

Rotational misalignment of two stacked honeycomb lattices produces a moiré pattern that is observable in scanning tunneling microscopy as a small modulation of the apparent surface height. This is known from experiments on highly-oriented pyrolytic graphite. Here, we observe the combined effect of three-layer moiré patterns in multilayer graphene grown on SiC (0001). Small-angle rotations between the first and third layer are shown to produce a "double-moiré" pattern, resulting from the interference of moiré patterns from the first three layers. These patterns are strongly affected by relative lattice strain between the layers. We model the moiré patterns as a beat-period of the mismatched reciprocal lattice vectors and show how these patterns can be used to determine the relative strain between lattices, in analogy to strain measurement by optical moiré interferometry.

Boron Nitride on Cu(111): An Electronically Corrugated Monolayer

“…a distortion of the hexagonal symmetry near domain boundaries (see Fig. 2b), indicating some strain in the h-BN layer 48 . Nevertheless, it can be concluded that BN on Cu(111) acts neither as a rigid overlayer keeping the bulk lattice constant like on Ag(111) 24 nor does it adapt a commensurate 1x1 structure as on Ni(111) 26 .…”

Evolution of microscopic localization in graphene in a magnetic field from scattering resonances to quantum dots

“…With the ability to control the charge density of Dirac fermions with an electrostatic back gate with fine resolution, which was missing in previous STS studies 5,[8][9][10][11][12][13][14] , we can investigate local density of states and localization in graphene at the atomic scale while varying the Fermi energy (E F ) with respect to the Dirac (charge neutrality, E D ) point. At zero magnetic field, we observe density fluctuations arising from the disorder potential variations due to charged impurities underneath the graphene.…”

“…As in semiconductor devices, these features are ultimately determined by electron interactions and scattering from disorder including the surrounding environment of the device. Direct access to the graphene with scanned probes allows for the measurement of these interactions in greater detail [4][5][6][7][8][9][10][11][12][13] than possible in conventional semiconductor devices where the transport layers are buried below the surface. For example, STS with atomic resolution has been used 4,5 to study the local density of states of graphene and the role of disorder at zero magnetic field.…”

Observation of the intrinsic bandgap behaviour in as-grown epitaxial twisted graphene

“…Bernal-stacked graphene shows quadratic energymomentum dispersion due to strong interlayer interaction and a bandgap opening due to symmetry breaking. Twisted graphene (TG) rotated by an arbitrary angle is commonly found in graphene grown on metals 3,9,10 , C-face SiC 11 or bulk graphite surfaces 12,13 , and is still under intensive study to identify its properties. Ab initio calculations showed that the Dirac cones and Fermi velocity of each layer preserved those of SLG due to decoupling between layers 14 .…”