Homogeneous Large-Area Quasi-Free-Standing Monolayer and Bilayer Graphene on SiC

Abstract

In this study, we first show that the argon flow during epitaxial graphene growth is an important parameter to control the quality of the buffer and the graphene layer. Atomic force microscopy (AFM) and low-energy electron diffraction (LEED) measurements reveal that the decomposition of the SiC substrate strongly depends on the Ar mass flow rate while pressure and temperature are kept constant. Our data are interpreted by a model based on the competition of the SiC decomposition rate, controlled by the Ar flow, with a uniform graphene buffer layer formation under the equilibrium process at the SiC surface. The proper choice of a set of growth parameters allows the growth of defect-free, ultra-smooth and coherent graphene-free buffer layer and bilayer-free monolayer graphene sheets which can be transformed into large-area high-quality quasi-freestanding monolayer and bilayer graphene (QFMLG and QFBLG) by hydrogen intercalation. AFM, scanning tunneling microscopy (STM), Raman spectroscopy and electronic transport measurements underline the excellent homogeneity of the resulting quasi-freestanding layers. Electronic transport measurements in four-point probe configuration reveal a homogeneous low resistance anisotropy on both μm-and mm scales.

Room temperature strain-induced Landau levels in graphene on a wafer-scale platform

“…1A), which appear similar to those reported on similar substrates ( 18 , 19 ). These nanoprisms appear during the growth process of graphene on 6H-SiC and are controllable by the Argon flow in the chamber ( 19 ). They cover between 5 and 10% of the terraces and are completely covered by monolayer graphene, the latter being demonstrated by our AFM adhesion images (see figs.…”

“…A population of triangular-shaped nanoscale features is identified on the terraces of our samples (Fig. 1A), which appear similar to those reported on similar substrates ( 18 , 19 ). These nanoprisms appear during the growth process of graphene on 6H-SiC and are controllable by the Argon flow in the chamber ( 19 ).…”

Traceably calibrated scanning Hall probe microscopy at room temperature

“…where ∂ e is the surface of the eth hexahedron with the normal unit vector n e and barycenter with vector position r e (Nabaei et al, 2013). The drift effect in the measured Hall voltage signal is well reconstructed by the numerical results, which also support the validity of the linear dependence of V Hall on B for all the scanning points, due to the large width of the pole scale with respect to the Hall cross size.…”

Silicon Carbide Stacking‐Order‐Induced Doping Variation in Epitaxial Graphene

“…This is attributed to an overcompensation of the polarization doping by electron transfer from a donor‐like buffer layer and interface states to the graphene layer. [ 4,5 ] Superimposed on these fundamental and spatially homogenous effects, the interplay between the hexagonal SiC and atop carbon layer is a source of various other intriguing phenomena, for example, step‐induced extrinsic resistance anisotropy in graphene, [ 6–9 ] dislocation boundary domains, [ 10 ] room temperature strain‐induced quantum Hall phase [ 11 ] and ballistic transport at SiC sidewalls, [ 12 ] the Stark effect, [ 13 ] and quantum photonics in SiC defect sites and color centers, [ 14 ] as well as offering an excellent platform for growing other low‐dimensional materials. [ 15–17 ] In general, the graphene properties on the SiC terraces are assumed to be uniform.…”