Effect of Channel Scaling on Zinc Oxide Thin-Film Transistor Prepared by Atomic Layer Deposition

Different active layer thicknesses for zinc oxide (ZnO) bottom-contact thin-film transistors (TFTs) were fabricated with a poly-4-vinyphenol polymeric dielectric using injector type atomic layer deposition. The properties of the ZnO TFTs were influenced by the active thickness and width-to-length (W/L) ratio of the device. The threshold voltage of ZnO TFTs shifted positively as the active layer thickness decreased, while the subthreshold slope decreased. The W/L ratio of ZnO TFTs also affected the mobility and subthreshold slope. An optimized TFT structure exhibited an on-tooff current ratio of above 106 with solid saturation.