2012 Volume 10 Pages 88-91
We investigated defects produced on a graphite surface by bombardment with gas cluster ions consisting of hundreds or thousands of argon atoms, and examined the structural changes of these defects by heat treatment. Two types of defects, craters and dots, were observed in STM images of the ion-bombarded surfaces. The production of these defects depends on the average kinetic energy per constituent atom of the cluster ion, and the threshold energy for the production of the crater and dot are 5 eV and 1.5 eV, respectively. After heating an ion-bombarded sample to 560°C in air, the craters changed to hexagonal pits and most of the dots disappeared, although a few (∼ 10%) dots changed to irregularly shaped pits. We describe the formation mechanisms of the two pit types on the basis of the oxidative etching of ion-induced defects. [DOI: 10.1380/ejssnt.2012.88]
