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

Flexible zinc oxide thin film transistors (ZnO TFTs) with a mobility of 13 cm
²
/V · s and an I
_on
/I
_off
ratio of 1.5×10
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.