Improved dynamic properties of ZnO-based photo-transistor with polymer gate dielectric by ultraviolet treatment

The authors report on the fabrication of photo-detecting top-gate ZnO-based thin-film transistors (ZnO-TFTs) with poly-4-vinylphenol (PVP) polymer gate dielectric. A ZnO channel surface was treated by intense ultraviolet (UV, wavelength of 352 nm) before making contacts with PVP dielectric. Although our UV-treated devices showed lower on-state current than untreated pristine ones, the former also displayed orders of magnitude lower off-state current than the latter. We applied the UV-treated devices for enhancing their photo-detection properties, which basically needs low off-state current. Under a modulated photon signal (10 Hz, 364 nm) for the UV detection measurements, our photo-inverter with UV-treated ZnO-TFT exhibited a good dynamic property of ∼30 ms operating at 5 V.