Self-Aligned Zno Thin-Film Transistors With 860 Mhz F(T) And 2 Ghz F(Max) For Large-Area Applications

High-frequency thin film transistors (TFTs) enable many important thin film circuits used in flexible large-area systems such as large bandwidth instrumentation amplifiers (related to f T ) and high-frequency oscillators (related to f max ) [1,2]. In [3] f max =10GHz and f T =2.9GHz were reported but using Si substrates and pulsed laser deposition for ZnO growth, which are incompatible with low-cost large-area processing on a meter scale. More modest reports of f max- =1GHz with sputtered IGZO on glass have relied on a very sensitive alignment process, impractical for fabrication over large substrates [4]. In this work we present a ZnO-channel TFT process fully compatible with flexible large-area substrates. We achieve an f max =2GHz and f T =860MHz by reducing source/drain (S/D) to gate overlaps (X ov ) and scaling channel lengths down to 500nm via a self-aligned process.