Abstract
The effect of O2+, H2++ O2+, and N2++ O2+ ion-beam irradiation of carbon nanotubes (CNTs) films on the chemical and electronic properties of the material is reported. The CNTs were grown by the chemical vapor deposition technique (CVD) on silicon TiN coated substrates previously decorated with Ni particles. The Ni decoration and TiN coating were successively deposited by ion-beam assisted deposition (IBAD) and afterwards the nanotubes were grown. The whole deposition procedure was performed in situ as well as the study of the effect of ion-beam irradiation on the CNTs by x-ray photoelectron spectroscopy (XPS). Raman scattering, field-effect emission gun scanning electron microscopy (FEG-SEM), and field emission (FE) measurements were performed ex situ. The experimental data show that: (a) the presence of either H2+ or N2+ ions in the irradiation beam determines the oxygen concentration remaining in the samples as well as the studied structural characteristics; (b) due to the experimental conditions used in the study, no morphological changes have been observed after irradiation of the CNTs; (c) the FE experiments indicate that the electron emission from the CNTs follows the Fowler-Nordheim model, and it is dependent on the oxygen concentration remaining in the samples; and (d) in association with FE results, the XPS data suggest that the formation of terminal quinone groups decreases the CNTs work function of the material.
Highlights
Irradiation on graphite in fusion experiments, and a straight forward comparison with our results is difficult.8 this limitation, our findings show that the low energy O2þ bombardment produces volatiles compounds (CO2 and CO) as reported with energetic O2þ ions probably by eliminating defective C sites
The experimental data show that: (a) the presence of either H2þ or N2þ ions in the irradiation beam determines the oxygen concentration remaining in the samples as well as the studied structural characteristics; (b) due to the experimental conditions used in the study, no morphological changes have been observed after irradiation of the carbon nanotubes (CNTs); (c) the field emission (FE) experiments indicate that the electron emission from the CNTs follows the Fowler-Nordheim model, and it is dependent on the oxygen concentration remaining in the samples; and (d) in association with FE results, the x-ray photoelectron spectroscopy (XPS) data suggest that the formation of terminal quinone groups decreases the CNTs work function of the material
In this paper we presented a comprehensive study of the effect of O2þ, H2þ þ O2þ, and N2þ þ O2þ ion-beam irradiation on the field emission properties of CNTs
Summary
Irradiation on graphite in fusion experiments, and a straight forward comparison with our results is difficult. this limitation, our findings show that the low energy O2þ bombardment produces volatiles compounds (CO2 and CO) as reported with energetic O2þ ions probably by eliminating defective C sites. Irradiation on graphite in fusion experiments, and a straight forward comparison with our results is difficult.8 This limitation, our findings show that the low energy O2þ bombardment produces volatiles compounds (CO2 and CO) as reported with energetic O2þ ions probably by eliminating defective C sites. The study of the microscopic mechanisms involved in the oxygen ion-beam irradiation of nanostructured graphene-based materials could improve our understanding as well as lead to further control of their electronic properties.. The effect of oxygen etching can be seen, for example, in Fig. 1 where a CNT structure presents flaws and dangling bonds These defects can react with oxygen species, which are either eliminated or, when remaining attached, act as network terminators. Based on the above facts, the aim of this paper is to investigate in situ the effect of O2þ, H2þþ O2þ, and N2þþ O2þ ion-beam irradiation on the electronic properties of CNTs deposited by CVD. As we shall see below, “carpet like” nanotubes are obtained from this procedure
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