High-Performance Flexible ZnO Thin-Film Transistors by Atomic Layer Deposition

Flexible zinc oxide thin film transistors (ZnO TFTs) with a mobility of $ {13}~\text {cm}^{2}/\text {V}\cdot \text {s}$ and an I $_{\text {on}}/\text{I}_{\text {off}}$ ratio of $ {1.5}\times {10}^{8}$ have been fabricated on polyimide substrate, where the ZnO channel is deposited by atomic layer deposition (ALD) at 140 °C. High bending stability has been achieved due to excellent interface quality between alumina (Al 2 O 3 ) dielectric and ZnO channel with a sharp interface topography. The flexible ZnO device exhibits excellent electrical characteristics even after being bent for 200 000 cycles with a tensile strain of 0.63%. Electrical measurement under a high tensile strain of 2.08% has also been carried out. Moreover, the electrical performance dependence of flexible ZnO TFTs with a tensile strain of 0.78% on temperature from 20 °C to 140 °C has been investigated for the first time.