title: Current saturation and voltage gain in bilayer graphene field effect transistors.
abstract: The emergence of graphene with its unique electrical properties has triggered hopes in the electronic devices community regarding its exploitation as a channel material in field effect transistors. Graphene is especially promising for devices working at frequencies in the 100 GHz range. So far, graphene field effect transistors (GFETs) have shown cutoff frequencies up to 300 GHz, while exhibiting poor voltage gains, another important figure of merit for analog high frequency applications. In the present work, we show that the voltage gain of GFETs can be improved significantly by using bilayer graphene, where a band gap is introduced through a vertical electric displacement field. At a displacement field of -1.7 V/nm the bilayer GFETs exhibit an intrinsic voltage gain up to 35, a factor of 6 higher than the voltage gain in corresponding monolayer GFETs. The transconductance, which limits the cutoff frequency of a transistor, is not degraded by the displacement field and is similar in both monolayer and bilayer GFETs. Using numerical simulations based on an atomistic p(z) tight-binding Hamiltonian we demonstrate that this approach can be extended to sub-100 nm gate lengths.
authors.affiliation: Advanced Microelectronic Center Aachen (AMICA), AMO GmbH, Otto-Blumenthal-Strasse 25, 52074 Aachen, Germany. szafranek@amo.de
authors.forename: B N
authors.initials: BN
authors.lastname: Szafranek
authors.forename: G
authors.initials: G
authors.lastname: Fiori
authors.forename: D
authors.initials: D
authors.lastname: Schall
authors.forename: D
authors.initials: D
authors.lastname: Neumaier
authors.forename: H
authors.initials: H
authors.lastname: Kurz
mesh_terms: D000669:Amplifiers, Electronic; D004553:Electric Conductivity; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006108:Graphite / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008567:Membranes, Artificial; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013499:Surface Properties; D014173:Transistors, Electronic
chemical_list: D046911:Macromolecular Substances; D008567:Membranes, Artificial; D006108:Graphite