Highly reliable growth process of carbon nanowalls using radical injection plasma-enhanced chemical vapor deposition

Abstract

Two-dimensional carbon nanostructures, carbon nanowalls (CNWs), were fabricated on a Si substrate using radical injection plasma-enhanced chemical vapor deposition, employing fluorocarbon (C2F6) and hydrogen (H2) mixtures. The influence of the surface conditions of the chamber wall on CNW growth was investigated in order to determine the optimum conditions for CNW growth with high stability and reproducibility. In order to monitor the surface conditions of the chamber wall, optical emission spectroscopy in the plasma was measured, and the correlation between CNW growth and the surface conditions in the chamber wall was investigated. The growth rate and morphology of grown CNWs were determined to be influenced by the surface conditions of the chamber wall. Furthermore, O2 plasma chamber cleaning followed by predeposition for passivation was found to be effective for maintaining steady conditions to attain CNWs with high reproducibility.

Formation and mechanism of ultrahigh density platinum nanoparticles on vertically grown graphene sheets by metal-organic chemical supercritical fluid deposition

“…Three characteristic peaks were found in the both spectra; G-band peaks at around 1582 cm −1 indicate a graphitized structure and the D-and DЈ-band peaks at 1356 cm −1 and 1620 cm −1 are attributed to the defect-induced phonon mode and finitesize graphite crystals, respectively. [16][17][18][19] The area ratios of the D-band to G-band peaks ͑I D / I G ͒ decreased from 2.5 to 1.7 as the CCP power was decreased, which indicates that the crystallinity of the CNWs was improved by decreasing the CCP power. The density ratios of carbon-related radicals to hydrogen radicals increases with an increase in the CCP power, which results in an increase in residual fluorine ͑F͒ atoms in the CNWs, which consequentially degrades the crystallinity of the CNWs.…”

“…On the other hand, the graphene sheets in the CNWs have huge amount of disorder, edges, and dangling bonds. [16][17][18][19] Therefore, to clarify the support mechanism of Pt nanoparticles on CNWs by MOCFD using ͑SC-CO 2 ͒, effects of those defects on the Pt nanoparticles supporting were discussed based on the comparison with the planar graphite substrates treated or untreated with an Ar/ H 2 gas mixture plasma to induce defects.…”

“…One is a parallel-plate very high frequency ͑VHF, 100 MHz͒ capacitively coupled plasma ͑CCP͒ to produce the carbon source and the other involves hydrogen radical injection source, which employs a surface-wave-excited microwave ͑2.45 GHz͒ plasma ͑SWP͒. 17 Hexafluoroethane ͑C 2 F 6 ͒ and H 2 molecular gases were separately introduced into the VHF-CCP region and radical source, respectively. The CCP and SWP were operated at 200 W, 270 W, and 250 W, respectively, and the flow rates of C 2 F 6 and H 2 were 50 SCCM and 100 SCCM, respectively ͑SCCM denotes cubic centimeter per minute at STP͒.…”

Carbon nanowall scaffold to control culturing of cervical cancer cells

“…Recently, establishing a radical injection plasma-enhanced chemical vapor deposition (RI-PECVD) system, we realized highly reproducible growth of CNWs, control of their morphology, and semiconducting properties. [12][13][14] Furthermore, chemical modification of the edges of CNWs and control of their surface wettability were also realized by post-growth plasma treatment. 15 These unique features and variety of modification available give CNWs a significant advantage and high potential for scaffold applications.…”

“…13 Three types of CNWs with different densities were prepared on quartz plates changing the total pressure, growth time, and CCP power. The flow rates of methane (CH 4 ) and hydrogen (H 2 ) were 50 and 100 sccm, respectively.…”