| AVS 58th Annual International Symposium and Exhibition | |
| Graphene and Related Materials Focus Topic | Friday Sessions |
| Session GR+MS+EM-FrM |
| Session: | Graphene Device Physics and Applications |
| Presenter: | Glenn Jernigan, U.S. Naval Research Laboratory |
| Authors: | G.G. Jernigan, U.S. Naval Research Laboratory T.J. Anderson, U.S. Naval Research Laboratory J.T. Robinson, U.S. Naval Research Laboratory J.D. Caldwell, U.S. Naval Research Laboratory M.D. Ancona, U.S. Naval Research Laboratory V.D. Wheeler, U.S. Naval Research Laboratory L.O. Nyakiti, U.S. Naval Research Laboratory J. Culbertson, U.S. Naval Research Laboratory A.L. Davidson, U.S. Naval Research Laboratory A.L. Friedman, U.S. Naval Research Laboratory P.M. Campbell, U.S. Naval Research Laboratory D.K. Gaskill, U.S. Naval Research Laboratory |
| Correspondent: | Click to Email |
Graphene has shown successful application in RF transistors and frequency doublers where its high mobility and high saturation velocity translate into operation at high frequencies while utilizing little power. However, a major detraction to graphene development for other device applications is that it does not have a band gap. The lack of a band gap means that graphene’s current cannot be turned off. Bilayer graphene is regarded as one possible solution to this problem, since bilayer graphene is capable of developing a band gap if the symmetry of the system can be broken. That said, bilayer graphene (from exfoliation or growth) forms a highly ordered A-B stack of the two graphene sheets resulting in little to no band gap, unless a high electric field can be applied.
In this presentation, we will demonstrate a novel method for creating bilayer graphene where a single layer of CVD graphene grown on Cu is bonded to a single layer of epitaxial graphene grown on Si-face SiC. This process results in a bilayer system that has a built-in asymmetry that yields unique physical and electrical properties not previously observed. For example, we demonstrate that the transfer of CVD graphene to epitaxial graphene results in a smoother morphology than transfer onto SiO2 and that bonding of CVD graphene to epitaxial graphene can avoid the damage caused by the drying step necessary in the poly (methyl methacrylate) transfer method. X-ray photoelectron spectroscopy and Raman microscopy demonstrate that the sheets are coupled together but strained differently, in contrast to a naturally formed bilayer. Electrical characterization of Hall devices fabricated on the novel bilayer show higher mobilities and lower carrier concentrations than the individual CVD graphene or epitaxial graphene sheets alone. Modeling of the electric field produced by opposite doping in the graphene sheets will also be presented, as CVD graphene is typically p-type and epitaxial graphene is typically n-type.