Surface superstructure of carbon clusters deposited on graphite during recrystallization

The recrystallization process of carbon clusters deposited on highly oriented pyrolytic graphite (HOPG) was investigated by scanning tunneling microscopy and high-resolution transmission electron microscopy. The carbon clusters deposited on HOPG at low coverage recrystallized epitaxially by annealing above 1623 K. The carbon clusters deposited at high coverage coalesced to form larger graphitic particles stacked with several layers of hexagonal planes in the annealing temperature range from 1873 to 2773 K. Four types of ringlike superstructures of (root 3x root3)R30 degrees of graphite, the circular type, the U-type, and the semicircular types I and II, were identified on the curved surface of these graphitic particles, and were well simulated by a modified interference model. (C) 2001 American Vacuum Society.