Catalyst-Free Carbon Nanowalls Grown On Glass And Silicon Substrates By Ecr-Mpcvd Method

Carbon nanowalls (CNWs) are vertically stacked graphene sheets that have an intermixed convoluted structure on the substrate. CNW can be used in energy storage devices, sensors, and fuel cells owing to the large surface. Increasing the wall height enlarges the total surface area and electro-optical properties of the film. However, the difficulty of depositing on a non-crystalline substrate and increasing the wall height are two major problems in terms of application areas. This problem can be overcome using an electron cyclotron resonance deposition system that enables high wall structures by controlling the kinetic energy and flow rate of reactive ions. CNWs were successfully deposited on a glass substrate without catalyst, using methane as the carbon source. Optimum CNW morphology was achieved at 1 keV ionization energy and 6 sccm gas flow rate. The height and width of the wall on the glass substrate were estimated as 216 nm and 1.5 mu m, respectively. Raman spectroscopy indicated that when 1 keV of critical ion energy was applied, sp(2)-bonded carbon phases in the structure were reduced, as well as sp(3)-bonded ones. The average optical transmittance of all films is over 90% and the band gap energy is in the range of 3.4-3.7 eV.