Professor Susan Fullerton, University of Pittsburgh
Using ions to control transport in 2D materials
Two-dimensional (2D) materials are molecularly thin, layered materials held together by van der Waals forces. Because charge moves freely in the 2D plane, these materials have potential application in electronics; however, conventional doping strategies have not been developed for 2D materials. An alternative approach is to use electrolyte gating. Under an applied gate voltage, ions in the electrolyte create an electrostatic double layer (EDL) at the interface between the electrolyte and the semiconductor; the EDL can induce sheet carrier densities on the order of 1014 cm-2 for both electrons and holes – more than one order of magnitude larger than conventional gating techniques. Our group seeks to translate EDL gating from a measurement tool for exploring transport to an active device component that enables new functionality at the ultimate limit of scaling. I will describe our work using polymer electrolytes to dope transistors based on graphene and transition metal dichalcogenides (TMDs), and our development of new types of electrolytes for applications in security and information storage. Specifically, I will introduce a monolayer electrolyte developed by our group and show the first device characteristics on graphene and MoS2 FETs.
Xu, K.; Lu, H.; Kinder, E.; Seabaugh, A.; Fullerton-Shirey, S.K. “Monolayer Solid State Electrolyte for Electric Double Layer Gating of Graphene Field-Effect Transistor” ACS Nano, 11 (6), 5453–5464 (2017).
Kinder, E.W.; Fuller, A.; Lin, Y-C.; Robinson, J.A.; Fullerton-Shirey, S.K. “Increasing the Room-Temperature Electric Double Layer Retention Time in Two-Dimensional Crystal FETs” ACS Appl. Mater. Interfaces, 9, 25006–25013 (2017).
Li, H.; Xu, K.; Buchanan, B.; Lu, H.; Lin, Y.-C.; Robinson, J.; Seabaugh, A.; Fullerton-Shirey, S.K. “Electric Double Layer Dynamics in Polyethylene Oxide LiClO4 on Graphene Transistors“ J. Phys. Chem. C., 121, 16996–17004 (2017).
This work was supported in part by the Center for Low Energy Systems Technology
(LEAST), one of six SRC STARnet Centers