Characteristics of Field Emitters on the Basis of Pd-Adsorbed ZnO Nanostructures by Photochemical Method

In this investigation, field electron emission (FE) performances of pure zinc oxide (ZnO) nanorod (NR) arrays and ZnO NRs with adsorbed palladium nanoparticles (Pd-ZnO) were explored under high-vacuum conditions. The nanostructures were successfully grown on substrates via a simple hydrothermal method (HM) and photochemical synthesis process. After characterizing the structural and crystal results of the as-grown samples, it was found that all NR structures were observed to be single crystals and presented structurally uniformity with the hexagonal wurtzite structures. Also, photoluminescence measurement was used to realize the optical properties of all samples. The results showed that pure ZnO and Pd-ZnO nanostructures exhibited two different emissions: one is an ultraviolet emission in the short wavelength and the other is green emissions. As for the field emitter performance, adsorbing with Pd nanoparticles reduced the turn-on field from 6.6 to 6.4 V/μm. The field enhancement factors (β) of pure ZnO (FE1) and Pd-ZnO NRs (FE2) were 2546 and 5947, respectively. The results revealed that the Pd-ZnO samples exhibited enhanced FE performances, which revealed the use of Pd-ZnO nanostructures as promising emitters for FE-based devices.