36.3: Flexible ZnO Thin‐Film Transistors Fabricated on PEN Substrate by Atomic Layer Deposition at Low Temperature

Flexible ZnO thin‐film transistors (TFTs) have been successfully fabricated by atomic layer deposition (ALD) on polyethylene naphthalate (PEN) substrate with a maximum processing temperature of 200 °C. The flexible ZnO TFTs show competitive electrical properties with high saturation mobility (μ sat ) of 17.5 cm 2 /Vs, small subthreshold slope (SS) of 91 mV/dec, high I on /I off of 3.8×10 9 and good uniformity. The larger characteristic trapping time τ for flexible ZnO TFT under NBS is the indication of less trapped charges compared with the device under PBS. In addition, we also investigate the mechanical bending test of flexible ZnO TFTs. The flexible ZnO TFTs exhibit a negative turn‐on voltage (V on ) shift and degraded SS with increasing tensile strains because the mechanical strain at the bending part of TFT channel generates donor‐like and acceptor‐like defects. Our results demonstrate that ALD process flexible ZnO TFTs exhibiting tremendous potential to be applicable in flexible electronics.