Nanoscale MoS2 Transistors on Polyimide for Radio-Frequency Operation

Two-dimensional (2D) materials are promising candidates for back-end-of-the-line (BEOL) integration and flexible electronics due to their low-temperature fabrication and layer transfer processes [1] . 2D field-effect transistors (FETs) provide opportunities for radio frequency (RF) front-ends for wireless communications in flexible systems. However, scaling the FET channel and gate length is key to achieving high-frequency performance. Previous studies have examined RF transistors from exfoliated MoS 2 on polyimide (PI) substrate, but sub-100-nm devices have only been demonstrated once [2] . Here, we demonstrate state-of-the-art RF FETs on PI, with gate lengths down to ~80 nm based on monolayer MoS 2 from chemical vapor deposition (CVD), with the highest transconductance ( g m ) reported for flexible MoS 2 RF FETs so far. We explore different contact metals and gate dielectrics, and compare the devices against our indium tin oxide (ITO) FETs, fabricated with a similar process, regarding their current densities, transconductance and RF performance.