High-Performance Current Saturating Graphene Field-Effect Transistor With Hexagonal Boron Nitride Dielectric on Flexible Polymeric Substrates

Graphene transistors using hexagonal boron nitride as the gate dielectric are implemented on mechanically flexible polyimide films. Current saturation is observed for the first time in graphene transistors on a plastic substrate. An atomically smooth insulating surface is achieved with the proposed capture-release process and two-step annealing process, resulting in subnanometer surface roughness. The device shows strong electrical performance: Extracted mobility exceeds 2300 cm²/V·s for both electron and hole transport, and drive current is over 300 μS/μm. This transport symmetry affords frequency doublers with high spectral purity and a conversion gain of - 29.5 dB and output power of -22.2 dBm, representing the highest performance for graphene transistors on flexible substrates.