Mechanics of hydrogenated amorphous carbon deposits from electron-beam-induced deposition of a paraffin precursor

Abstract

Many experiments on the mechanics of nanostructures require the creation of rigid clamps at specific locations. In this work, electron-beam-induced deposition ͑EBID͒ has been used to deposit carbon films that are similar to those that have recently been used for clamping nanostructures. The film deposition rate was accelerated by placing a paraffin source of hydrocarbon near the area where the EBID deposits were made. High-resolution transmission electron microscopy, electron-energy-loss spectroscopy, Raman spectroscopy, secondary-ion-mass spectrometry, and nanoindentation were used to characterize the chemical composition and the mechanics of the carbonaceous deposits. The typical EBID deposit was found to be hydrogenated amorphous carbon ͑a-C:H͒ having more sp 2 -than sp 3 -bonded carbon. Nanoindentation tests revealed a hardness of ϳ4 GPa and an elastic modulus of 30-60 GPa, depending on the accelerating voltage. This reflects a relatively soft film, which is built out of precursor molecular ions impacting the growing surface layer with low energies. The use of such deposits as clamps for tensile tests of poly͑acrylonitrile͒-based carbon nanofibers loaded between opposing atomic force microscope cantilevers is presented as an example application

Electron flux controlled switching between electron beam induced etching and deposition

“…Below, we demonstrate the proposed behavior using a model of simultaneous etching and deposition. In the model, we eliminate the effects of precursor molecule surface diffusion and of the beam revisit period 31,50,51 by considering the case of an electron-irradiated semi-infinite surface. We assume that both etch and deposit precursors arrive from vacuum, with arrival rates determined by their respective partial pressures.…”

Modulus, Fracture Strength, and Brittle vs. Plastic Response of the Outer Shell of Arc-grown Multi-walled Carbon Nanotubes

“…TEM observation revealed that the layer thickness ranged from 1-10 nm. According to our previous work [36], the deposit consists of hydrogenated amorphous carbon having an elastic modulus roughly in the range 30-60 GPa. If the EBID deposit is also bearing load, the tensile stress supported by the outermost shell is overestimated in our analysis, and thus the strength and modulus values would be as well.…”

Elastic modulus of amorphous SiO2 nanowires

“…In order to avoid nanowire sliding during the bending tests, both ends of the nanowires, which bridged the channel, were clamped by electron-beaminduced deposition ͑EBID͒ of carbonaceous materials ͑paraffin͒. 36 A Veeco Dimension 3100 AFM was used to perform three-point bending tests by directly indenting the center of a suspended nanowire which bridged the channel with a tapping mode silicon AFM tip. Figure 1͑a͒ shows the SEM image of the as-grown SiO 2 nanowires.…”