Multilayer Epitaxial Graphene: The New Substrate for Graphene Electronics - Edward Conrad
From Katie Gentilello
Graphene has been advertised both as a unique electron system for 2D physics research and as a platform for carbon electronics. Despite these claims, only a few of the fundamental properties of an isolated graphene sheet have been demonstrated in a single system. This is because of substrate interactions in both exfoliated graphene on SiO2 and epitaxial graphene grown on the Si-face of SiC. Disorder even in supported exfoliated films and the inability to scale these geometries to large circuit platforms reflect similar problems that have plagued carbon nanotubes for more than two decades and prevented them from any significant role in post Si-CMOS technologies. Despite these sobering realities, an all carbon electronics system is still very likely. The remarkable finding is that the system most likely to be developed into a carbon electronics paradigm is the one initially dismissed by graphene researchers. I will show that only one graphene system has demonstrated the properties expected for an isolated graphene sheet: multilayer epitaxial graphene (MEG) grown on the C-face of SiC. MEG not only shows all the 2D properties expected for an isolated graphene sheet, but has the scalability to be expanded to large scale integrated carbon circuits. I will show that the reason for this remarkable property, i.e. a multilayer graphene films behaving like a single graphene sheet, is due to MEG’s unique stacking. MEG films have a quasi-ordered rotational stacking that breaks the Bernal stacking symmetry associated with both graphite and thin graphene sheets grown on the Si-face of SiC. LEED, X-ray scattering, ARPES and transport measurements will all be presented that demonstrate the MEG’s isolated graphene electronic properties. I will also show how furnace grown MEG films on the C-face can be produced in exceptional sizes. Growth on step free regions up to 40microns with film thickness variations of one layer over millimeters can now be achieved and seem to be only limited by the SiC substrate perfection.