Carbon cone arrays by double-bias assisted hot filament plasma chemical vapor deposition

Abstract

Double-bias-assisted hot-filament chemical vapor deposition has been applied for the formation of micro- and nano-sized cones on Si substrates during deposition of diamond-like carbon (DLC) films. It is found that the grid current strongly affects the substrate current–voltage characteristics due to the adding of ion fluxes from the grid region to the substrate region. High-density carbon needles are initially aligned, and then large-scale cones form as the growth time is increased. An intrinsic model that carbon of sp 3 phase serves as the etching mask is proposed for the cone formation. With a further increase of the growth time, these cones sharpen, and there presents higher density of cone because of the secondary nucleation effect. The sizes of cones change with the grid and substrate currents. These results indicate that a tuning of the relative fluxes of ions and reactive species on growing surface can be achieved in this double biasing system, which provides a possibility of structuring surface geometry for DLC films.