Graphene Transistors on Mechanically Flexible Polyimide Incorporating Atomic-Layer-Deposited Gate Dielectric

Transistors are constructed using chemical vapor-deposited graphene on mechanically flexible polyimide and incorporate a low-temperature atomic-layer-deposited gate dielectric. Three-micrometer gate length transistors with V
_ds
= 2.0 V have a drive current of >; 0.3 A/mm with a transconductance of >; 3 mS/mm. The peak hole and electron mobilities are 295 and 106 cm
²
/V · s, respectively. Subsequent to repeated flexing, the ambipolar characteristics and extremely low gate leakage remain intact with <; 15% reduction in the peak carrier mobility. Good agreement is obtained between the measured mobility and a physically based empirical model and is consistent with the mobility limited by impurity levels and surface roughness. Using graphene-on-polyimide transistors, radio-frequency functionalities, including signal amplification and phase shifting, are demonstrated, and routes for performance improvement are discussed. The results are important for the development of graphene-based electronics on mechanically flexible substrates.