Science2016 Susan Fullerton: Using Ions To Control Transport in Two-Dimensional Materials for Electronics 

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. I will describe our work using electrolytes to dope transistors and memory devices based on graphene and transition metal dichalcogenides (TMDs). Our group has developed a 2D electrolyte for use in memory devices based on 2D crystals, and the first device characteristics will be presented. 
This work was supported in part by the Center for Low Energy Systems Technology (LEAST), one of six SRC STARnet Centers, sponsored by MARCO and DARPA, and NSF grant #ECCSGOALI-1408425.