High-frequency prospects of 2D nanomaterials for flexible nanoelectronics from baseband to sub-THz devices

We report on the state of the art sub-μm length (L) flexible two dimensional radio frequency thin film transistors operating in the velocity saturation regime for achieving maximum carrier transport or under high-field. We realize large-area monolayer MoS₂ on flexible polyimide with 5 GHz cut-off frequency (f_T), a record value for flexible synthesized transitional metal dichalcogenides (TMDs). For higher frequency devices, flexible black phosphorus (BP) RF TFT is demonstrated for the first time with f_T ~ 17.5 GHz for L = 0.5 μm, yielding v_sat ~ 5.5 × 10⁶ cm/s. In addition, for flexible sub-THz nanosystem front-ends, we have achieved record 100 GHz graphene TFTs (v_sat ~ 8.8 × 106 cm/s) on flexible glass, 56% higher than that of graphene TFTs on polymeric substrates.