Oxide Semiconductor Thin Film Transistors on Thin Solution-Cast Flexible Substrates

We report ZnO thin-film transistors (TFTs) fabricated on solution-cast thin polyimide flexible substrates. Plasma-enhanced atomic layer deposition was used to deposit ZnO semiconductor and Al₂O₃ dielectric layers and the highest processing temperature used was 200 °C. The TFTs fabricated on thin polyimide substrates have characteristics very similar to devices fabricated on glass substrates and device characteristics changed little with release from the casting substrate. Typical TFT mobility was >12 cm²/V·s for a gate electric field of 2 MV/cm. Released substrates with the TFTs were flexed between 3.5-mm radius and flat for 50000 cycles with little change in device characteristics. These results demonstrate solution casting of thin polymer layer substrates as a simple path to oxide semiconductor flexible electronics.