Electromigration of Ag Ultrathin Films on Si (111) 7×7

Scanning Auger electron spectroscopy observation revealed that a patch of Ag thin film with a thickness of several monolayers spread on the cathode side over the clean surface of Si(111) 7×7 with the application of dc current to the Si substrate. The spread-out layer had the constant thickness of 1.0 monolayer (=7.8×1014 atom/cm2) with √3×√3 structure. On the anode side the edge of the patch made no significant movement but a mixed phase of √3×√3 and 3×1 with a thickness of 0.8 monolayer appeared and extended from the edge toward the cathode. The mass transport was correlated with changes in the structure of the overlayer.