High Rate of Hydrogen Incorporation in Vertically Aligned Carbon Nanotubes during Initial Stages of Growth Quantified by Elastic Recoil Detection

Abstract

We quantified the amount of hydrogen in as-grown vertically aligned multiwall CNTs at different stages of growth using elastic recoil detection analysis (ERDA). We suggest that hydrogen is associated with atomic defects and/or amorphous carbon impurities formed at earlier deposition stages. We found that the highest amount of hydrogen (2.3 wt %) was incorporated during the initial growth stage (15–20 s). Our results show a decrease of hydrogen content with increasing deposition time and/or with decreasing growth rate, which points to dynamical self-annealing of hydrogen-saturated defects. Consequently, the decrease of hydrogen-related defects leads to a higher quality of MWCNTs, which can be easily detected by ERDA. This research provides new insight into the nanotube growth mechanism and provides a new characterization approach for quantifying hydrogen-saturated atomic defects in MWCNTs.

Morphology, Microstructure, and Hydrogen Content of Carbon Nanostructures Obtained by PECVD at Various Temperatures

“…Datta et al [11] suggest that in amorphous carbon the decrease could be the consequence of the formation of graphitic structure with less sp 3 carbon towards the Si substrate. In VA-CNT structure, Gouzman et al [21] suggested the appearance of amorphous carbon impurities (with high hydrogen content) around the tube. For CNW, there are no reports: we hypothesize that lower energy losses per unit path are valid in the very porous material for the incident 4 He 2+ ions particles, which would travel obliquely across the spatially separated thin graphene stacks.…”

Thin film depth profiling by ion beam analysis

“…In this case only hydrogen isotope recoils have the energy to penetrate the range foil, so the standard silicon detector may be used without damage and there is no signal/ noise problem. This simple method remains important 163 because hydrogen is otherwise difficult to depth profile quantitatively, and because it is very easy to combine with standard RBS.…”