No abstract

We demonstrate the growth of high quality graphene layers by chemical vapor deposition (CVD) on insulating and conductive SiC substrates. This method provides key advantages over the well-developed epitaxial graphene growth by Si sublimation that has been known for decades. (1) CVD growth is much less sensitive to SiC surface defects resulting in high electron mobilities of ∼1800 cm(2)/(V s) and enables the controlled synthesis of a determined number of graphene layers with a defined doping level. The high quality of graphene is evidenced by a unique combination of angle-resolved photoemission spectroscopy, Raman spectroscopy, transport measurements, scanning tunneling microscopy and ellipsometry. Our measurements indicate that CVD grown graphene is under less compressive strain than its epitaxial counterpart and confirms the existence of an electronic energy band gap. These features are essential for future applications of graphene electronics based on wafer scale graphene growth.

No abstract

No abstract

The energy dependence of the electronic scattering time is probed by Landau level spectroscopy in quasineutral multilayer epitaxial graphene. From the broadening of overlapping Landau levels we find that the scattering rate 1/τ increases linearly with energy ϵ. This implies a surprising property of the Landau level spectrum in graphene-the number of resolved Landau levels remains constant with the applied magnetic field. Insights are given about possible scattering mechanisms and carrier mobilities in the graphene system investigated.