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Homogeneous Large-area Quasi-freestanding Monolayer and Bilayer Graphene on SiC
摘要： 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 by hydrogen intercalation. AFM, scanning tunneling microscopy, 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.
关键词： SiC terrace steps,polymer assisted sublimation growth,Epitaxial graphene,freestanding bilayer graphene,argon gas flow,graphene buffer layer,monolayer graphene,resistance anisotropy,large-scale graphene growth,freestanding monolayer graphene
更新于2025-09-23 15:22:29
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Reduced energy-angle dispersion of output electrons from a nanocrystalline Si emitter with a monolayergraphene surface electrode
摘要： It is shown that the angle dispersions of output electrons of nanocrystalline silicon (nc-Si) quasiballistic electron emitter are significantly reduced by using a monolayer graphene as the surface electrode. This is closely linked with a remarkable enhancement in the emission efficiency and a suppression of the electron energy dispersion. The angle distribution curves become more directional at lower temperatures. These results are attributed to high transparency of monolayer graphene for quasiballistic electrons generated in the nc-Si layer. The intrinsic multi-tunneling cascade mode through nc-Si dots can be utilized most effectively by monolayer graphene surface electrode.
关键词： quasiballistic emission,monolayer graphene,nanocrystalline silicon
更新于2025-09-23 15:21:21