Formation of Epitaxial Graphene Layers on 6H-SiC Induced by Electron Beam Irradiation

Abstract

It is observed that the epitaxial graphene layers form on the surface of a 6H-SiC substrate by electron beam irradiation. The electron beam (e-beam) is irradiated by using a commercial electron beam evaporator with acceleration voltage 8kV in high vacuum environment. Raman spectrum measurements show all relevant peaks (D, G, 2D) clearly, confirming the formation of graphene layers. The structural analysis is confirmed by using TEM (Transmission Electron Microscopy). The result of formed graphene layers thickness measurement is verified 7 ~ 8 layers of graphene. It is checked out that thickness of 1 layer is approximately 0.32 nm. The elemental composition of the epitaxial graphene layer is measured with AES (Auger Electron Spectroscopy) and XPS (X-ray Photoelectron Spectroscopy). The sheet resistance of the epitaxial graphene layer which is measured by forming CTLM (Circular Transmission Line Model) patterns on the irradiated 6H-SiC surface is found to decrease at least 1000 times, compared with the original 6H-SiC substrate. The sheet resistance and contact resistance of graphene layer are 6.7 kΩ/□ and 0.18 kΩ respectively. Also, the quality of the graphene layer in terms of Raman spectrum and sheet resistance is found to be improved noticeably as the electron fluence (e/cm2) is increased by making the irradiation time longer.