Density control of carbon nanowalls grown by CH4/H2 plasma and their electrical properties

We report on successful control of the density of carbon nanowalls (CNWs) synthesized using radical-injection plasma-enhanced chemical vapor deposition (RI-PECVD) employing CH4/H2 plasma, by varying the total pressure and discharge power during growth. As the total pressure was decreased or the power was increased, the density of CNWs decreased in conjunction with an increase in the H atom density measured using actinometric optical emission spectroscopy. The electrical conductivity of the films was found to be determined by the number of CNWs per unit length, i.e., the linear density. We demonstrated that the electrical properties could be controlled while maintaining the crystal quality and chemical bonding state of the synthesized CNWs in the RI-PECVD.