Influence of NiO ALD Coatings on the Field Emission Characteristic of CNT Arrays

Abstract

The paper presents a study of a large-area field emitter based on a composite of vertically aligned carbon nanotubes covered with a continuous and conformal layer of nickel oxide by the atomic layer deposition method. The arrays of carbon nanotubes were grown by direct current plasma-enhanced chemical vapor deposition on a pure Si substrate using a nickel oxide catalyst which was also deposited by atomic layer deposition. The emission characteristics of an array of pure vertically oriented carbon nanotubes with a structure identical in morphology, covered with a layer of thin nickel oxide, are compared using the data from a unique computerized field emission projector. The deposition of an oxide coating favorably affected the emission current fluctuations, reducing them from 40% to 15% for a pristine carbon nanotube and carbon nanotube/nickel oxide, respectively. However, the 7.5 nm nickel oxide layer coating leads to an increase in the turn-on field from 6.2 to 9.7 V/µm.

Reducing and tuning the work function of field emission nanocomposite CNT/NiO cathodes by modifying the chemical composition of the oxide

“…Thus, according to the E th values and results of processing the current-voltage characteristics, coating NiO on the surface of CNTs after heat treatment at 350 °C improved the field emission efficiency, since the work function of the structures, as was shown in the previous paragraph of the work, decreases. In our previous work, 68 we showed a decrease in the efficiency of field emission when NiO was deposited on CNTs without heat treatment, which resulted in an increase in the field for producing an emission current density of 10 μA cm −2 from 6.16 V μm −1 ( pure CNTs) to 9.66 V μm −1 (CNT/NiO). The deterioration of the emission current-voltage characteristic occurred due to the fact that the stoichiometric oxide had a higher work function.…”