• 文献标题:   Homogeneous Large-Area Quasi-Free-Standing Monolayer and Bilayer Graphene on SiC
  • 文献类型:   Article
  • 作  者:   PAKDEHI DM, PIERZ K, WUNDRACK S, APROJANZ J, NGUYEN TTN, DZIOMBA T, HOHLS F, BAKIN A, STOSCH R, TEGENKAMP C, AHLERS FJ, SCHUMACHER HW
  • 作者关键词:   epitaxial graphene, argon gas flow, graphene buffer layer, largescale graphene growth, resistance anisotropy, sic terrace step, monolayer graphene, freestanding monolayer graphene, freestanding bilayer graphene, polymerassisted sublimation growth
  • 出版物名称:   ACS APPLIED NANO MATERIALS
  • ISSN:   2574-0970
  • 通讯作者地址:   Phys Tech Bundesanstalt
  • 被引频次:   8
  • DOI:   10.1021/acsanm.8b02093
  • 出版年:   2019

▎ 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 a defect-free, ultrasmooth, and coherent graphene-free buffer layer and bilayer-free monolayer graphene sheets which can be transformed into large-area high-quality quasi-free-standing 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-free-standing layers. Electronic transport measurements in four-point probe configuration reveal a homogeneous low resistance anisotropy on both mu m and mm scales.