The degrees of graphitization of carbon films grown by photoemission-assisted plasma-enhanced chemical vapor deposition were evaluated by hard-X-ray photoemission spectroscopy (HAXPES). The films were grown with a CH4/He or CH4/Ar mixture at growth temperatures from 400 to 1000 °C. Low-temperature growth was mainly focused on. The result of HAXPES showed that the films dominantly have sp2 bonding states. The film grown at 400 °C with CH4/Ar had an sp2 content of 84%, which was comparable to those of the films grown at temperatures ≥800 °C. The orientation of the graphitic grains was also examined by soft-X-ray absorption spectroscopy. The degrees of orientation of the films were up to 70%, compared to that of highly oriented pyrolytic graphite. The film grown at 400 °C with CH4/Ar had the degree of graphitization of ∼40%, which was comparable to that for the film grown at 800 °C with CH4/He.

Photoemission-assisted plasma-enhanced chemical vapor deposition (PA-PECVD), a process in which photoelectrons emitted from a substrate irradiated with ultraviolet light are utilized as a trigger for DC discharge, was investigated in this study; specifically, the DC discharge characteristics of PA-PECVD were examined for an Si substrate deposited in advance through hot-filament chemical vapor deposition with a nitrogen-doped diamond layer of thickness ∼1 μm. Using a commercially available Xe excimer lamp (hν = 7.2 eV) to illuminate the diamond surface with and without hydrogen termination, the photocurrents were found to be 3.17 × 1012 and 2.11 × 1011 electrons/cm2/s, respectively. The 15-fold increase in photocurrent was ascribed to negative electron affinity (NEA) caused by hydrogen termination on the diamond surfaces. The DC discharge characteristics revealed that a transition bias voltage from a Townsend-to-glow discharge was considerably decreased because of NEA (from 490 to 373 V for H2 gas and from 330 to 200 V for Ar gas), enabling a reduction in electric power consumption needed to synthesize diamond films through PA-PECVD. In fact, the authors have succeeded in growing high-quality diamond films of area 2.0 cm2 at 540 °C with a discharge power of only 1.8 W, plasma voltage of 156.4 V, and discharge current of 11.7 mA under the glow discharge of CH4/H2/Ar mixed gases. In addition to having only negligible amounts of graphite and amorphous carbon, the diamond films exhibit a relatively high diamond growth rate of 0.5 μm/h at temperatures as low as 540 °C, which is attributed to Ar+ ions impinging on the diamond surface, and causing the removal of hydrogen atoms from the surface through sputtering. This process leads to enhanced CHx radical adsorption, because the sample was applied with a negative potential to accelerate photoelectrons in PA-PECVD.

A method of outer surface modification of glass nanopipette with chlorobenzene-terminated organopolysiloxane has been developed. Scanning electron microscope images and microscopic Raman spectra revealed the efficacy of the coating. Energy dispersive X-ray spectra showed not only the materials adsorbed on the nanopipette but also the change in stoichiometry of the bulk glass resulting from the fabrication process of the nanopipette with a laser puller. The coating method is easy to treat and can be used for various applications such as the prevention of carbon contamination from the materials during the injection to biomaterials such as living cells.

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