Generation of carbon nanowhiskers, nanotips, and nanodots by controlling plasma environment: Ion energy and radical effects

Abstract Carbon nanotips and nanowhiskers were produced through etching of an amorphous carbon layer (ACL) by controlling the plasma environment. Discharge types and different gases induced significant changes in the carbon nanostructure owing to the independent or combined effect of ions and radicals. The carbon nanowhiskers were obtained by both ion bombardment and oxygen radicals in a radiofrequency (RF) capacitively coupled plasma (CCP) under the O2 gas environment. In contrast, RF CCP in an Ar gas environment or inductively coupled plasma (ICP) in an O2 gas environment formed carbon nanotips or nanodots, respectively, through the rearrangement of carbon atoms due to ion bombardment or chemical etching by radicals. The carbon nanowhiskers and nanotips were vertically grown in these plasma conditions due to the effect of an electric field, and its effect on the vertical growth was confirmed when using ICPs with RF bias where the electric field in a plasma sheath is controlled. Raman spectroscopy and high-resolution transmission electron microscopy measurements indicate that the crystalline area in carbon nanostructures increased during the rearrangement of the ACL induced by ion bombardment and radical reaction.