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

Abstract

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 MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> on flexible polyimide with 5 GHz cut-off frequency (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> ), 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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> ~ 17.5 GHz for L = 0.5 μm, yielding v <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sat</sub> ~ 5.5 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> cm/s. In addition, for flexible sub-THz nanosystem front-ends, we have achieved record 100 GHz graphene TFTs (v <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sat</sub> ~ 8.8 × 106 cm/s) on flexible glass, 56% higher than that of graphene TFTs on polymeric substrates.