Graphene Transistors Gated by Salted Proton Conductor

The first use of proton conductors for gating graphene transistors is demonstrated. The proton conductor used in this study, [poly(styrenesulfonic acid)], is added with sodium halide salts in order to improve the capacitive characteristics of the electrolyte gate dielectric. The influence of the added sodium halide salts (NaF, NaCl, NaBr, and NaI), the salt concentration, and the relative humidity on the dielectric properties of the electrolyte are investigated systematically. Substantial enhancement in the device performances of the graphene transistors including carrier mobility, device ON current, Dirac voltage, and device cut-off frequency is attained with the addition of the sodium halide salts. From the optimized conditions based on NaI salts, the graphene transistors exhibit hole and electron mobilities of 1900 and 990 cm² V^–1 s^–1, respectively, with Dirac voltage near 0 V. Moreover, the cut-off frequency of the device presenting the dynamic characteristics of a transistor reach up to 100 kHz.