Fabrication of carbon nanowalls by dc plasma-enhanced chemical vapor deposition and characterization of their structures

Two-dimensional carbon nanostructures called carbon nanowalls (CNWs) were fabricated using dc plasma-enhanced chemical vapor deposition with a gas mixture of CH₄, H₂ and Ar. CNWs were vertically grown on quartz and Si substrates at temperatures of 500 to 800°C. The size of CNWs was controlled by growth conditions such as CH₄/H₂ ratio and substrate temperature. The structures of CNWs were characterized by Raman spectroscopy. The spectral features of CNWs are distinguished from those of typical graphite-like carbons reported so far. From the comparison of the spectral features, it is shown that CNWs are composed of small crystallites with a high degree of graphitization.