Migration of Metals on Graphite in Scanning Tunneling Microscopy.

Metals such as Au deposited on graphite substrates are found to migrate very easily when biased in scanning tunneling microscopes. Depending upon the film thickness and the tip voltage, a hillock surrounded by grooves or a hole surrounded by hillocks with a height of ~±10 nm and a lateral dimension of ~100 nm are formed. The mechanism of these surface-modification phenomena is discussed in light of electro- and thermomigration.