Enhanced field emission properties of ZnO:Al/SrTiO${}_3$ perovskite composite films by ZnO:Al film

ZnO:Al(Al-doped zinc oxide)/SrTiO${}_3$ composite thin film field emission (FE) devices are fabricated on heavily doped n-type silicon substrates using a vacuum electron beam evaporation vapor deposition technique and hydrogen plasma treated technique. The morphology and thickness of SrTiO${}_3$ film and ZnO:Al film are controlled by adjusting and optimizing the growth conditions, deposition time, and post-treatment conditions. FE experimental results show that the addition of ZnO:Al films can significantly improve the FE properties of ZnO:Al/SrTiO${}_3$ composite film. The maximum current density of the FE sample increases from 230 µA cm${}^{-2}$ of the monolayer SrTiO${}_3$ film sample, which is treated by hydrogen plasma (H-SrTiO${}_3$) to 951 µA cm${}^{-2}$ of the ZnO:Al/H-SrTiO${}_3$ composite film sample, which increases by more than 4 times. Meanwhile, at the applied electric field intensity of 3.6 V µm${}^{-1}$, the FE current density of ZnO:Al/H-SrTiO${}_3$ composite film is 48 times that of monolayer H-SrTiO${}_3$ film. Each field emission sample device has good working stability and experimental repeatability. (© 2022 Wiley-VCH GmbH)