Scaled Graphene Nanoribbon Transistors for Ultra-High Frequency Applications

• Applicants: Dr. Jörg Pezoldt; Privatdozent Dr.-Ing. Frank Schwierz
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: from 2013 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 242384773

Since 2004, graphene has gained enormous attention. In particular the outstanding carrier transport properties of this material have spurred worldwide efforts on using graphene channels for next-generation transistors. Currently intensive research on graphene transistors for RF (radio frequency) applications is underway and graphene MOSFETs showing competitive cutoff frequencies in excess of 300 GHz have been demonstrated. Unfortunately, the much more important maximum frequency of oscillation fmax of these transistors is still below 50 GHz, i.e., much lower than that of conventional RF transistors. Recently it has been shown that the poor fmax performance of all RF graphene MOSFETs reported so far is caused by their gapless channel and that a semiconducting graphene channel is needed to improve the fmax performance. This finding provides the motivation of the present project which is focused on GNR (graphene nanoribbon) MOSFETs for RF operation. In the project, GNRs with a gap wide enough for proper RF operation will be used as MOSFET channels and in-depth research on RF GNR MOSFETs will be conducted. The two project partners with recognized expertise in RF transistor theory and graphene technology will deal with the following tasks:- Theoretical investigation of the DC and RF behavior of GNR MOSFETs.- Elaboration of suitable designs for high-performance RF GNR MOSFETs. - Fabrication of GNR MOSFETs using epitaxial graphene produced in-house and semiconducting graphene provided by other groups of the SPP as starting material. - Material analysis and electrical characterization (DC and RF including RF noise) of GNR MOSFETs. - Investigation of the scaling behavior and performance limits RF graphene MOSFETs. Extensive device simulations will be performed to get better insights in the physics of GNR MOSFETs. The results serve as basis for the elaboration of suitable designs for the RF GNR MOSFETs to be fabricated. Key targets of the project are (i) the realization of RF GNR MOSFETs with GNR widths and gate lengths down to 10 nm and improved performance (in particular fmax) and (ii) a significant enhancement of the understanding of the physics of GNR MOSFETs and a well-founded assessment of their potential.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1459: Graphen