Electrical regulation of multilayer graphene and graphene nanoscrolls using deionized water as a gate dielectric

Graphene and related two-dimensional (2D) materials exhibit exceptional carrier mobility and scalability, making them promising candidates for next-generation field-effect transistors (FETs). However, the electrostatic control provided by conventional back-gate configurations deteriorates rapidly with increasing channel thickness, severely limiting effective gating in multilayer structures. Here, we demonstrate an effective gating strategy using deionized (DI) water as a solution-based top gate for multilayer graphene (often referred to as thick-layer graphene in this work) field-effect transistors. The DI water gate offers strong electrostatic control, fast bias response, and low-voltage access to the Dirac point. Most notably, as the major novelty of this work, we demonstrate the unprecedented combination of a DI water gate with a graphene nanoscroll (GNS) channel. This strategy is attributed to the high mobility of ions, which can be driven by the electric field to penetrate into the interlayer regions and establish electrostatic coupling with individual 2D layers. Furthermore, DI water-gated GNS FETs exhibit significant potential for sensing applications. GNS-based field-effect transistors also demonstrate a significantly higher maximum current density than conventional graphene devices, suggesting a viable route toward higher power density and improved device reliability. Here, the current density is defined as the drain current normalized by the effective channel width. These results highlight DI water gating as an elegant, robust, and scalable approach for modulating multilayer and scroll-type 2D material devices, paving the way for advanced nanoelectronic and sensing technologies.