Fabrication of Atomic Layer Deposited Zinc Oxide Thin Film Transistors with Organic Gate Insulator on Flexible Substrate

Abstract

In the fabrication of transparent conductive oxide thin film transistor (TFT), an atomic layer deposited (ALD) zinc oxide (ZnO) and a cross-linked poly-vinyl-alcohol (c-PVA) were each used as active layer and gate insulating layer on poly-ethylene (PET) substrate respectively. Considering the transmittance and the deposition rate of the ALD ZnO at a low temperature without any damage on PET substrate, the ZnO layer was deposited at a temperature of 120°C on a spin-coated c-PVA layer. From the atomic force microscope (AFM) images, it was possible to conclude that the surface morphologies of ZnO deposited on a c-PVA layer was not inferior to those of ZnO deposited on bare-Si and that the c-PVA can be used as a gate insulator at 120°C. The fabricated ZnO TFT showed good electrical characteristics such as the mobility of 0.1 cm2/V · s, on-off current ratio of 4.5 × 104.