Advances in the Fabrication of Large-Area Back-Gated Graphene Field-Effect Transistors on Plastics: Platform for Flexible Electronics and Sensing

Abstract

Graphene (Gr) is currently one of the most appealing materials as conductive transparent electrode for flexible electronics, thanks to its bendability/stretchability accompanied by small variations of the electrical properties after mechanical deformations. In addition, the field-effect tunable carrier density combined to a high mobility and saturation velocity make it an excellent channel material for field-effect transistors (FETs) even on flexible substrates. By proper design of the device structure (channel length, top- or back-gate configuration), Gr-FETs can be used for high-frequency (RF) electronics or for high-sensitivity chemical, biological, and environmental sensors exploiting transconductance variations in response to the chemi/physisorption of molecular species on Gr channel. In particular, miniaturized and flexible Gr-FET sensors can represent a strong advance with respect to current sensors technology and will be extremely useful for “in situ” applications. Here we report a wafer scale and semiconductor fab compatible processing strategy to fabricate arrays of Gr-FETs on a PEN substrate, adopting a local back-gate configuration, with a thin Al2O3 gate dielectric film deposited at low temperature (100 °C) by plasma-assisted Atomic Layer Deposition (ALD) and transfer of large-area Gr grown by chemical vapor deposition on copper foils. Electrical characterization of the fabricated devices is presented and their suitability for solid ion sensing FET (IS-FET) applications is discussed.