Size Scaling in the Decay of Metastable Structures

The rate of thermal decay of special fabricated structures on Si(111) has been measured for structure sizes ranging from 28 to 50 Å high. The mechanism of the decay via motion of individual steps has been observed directly using scanning tunneling microscopy. The results are consistent with size-scaling predictions of theory, and show that mass transport occurs via a mechanism in which mass is conserved locally. In addition, the theory yields a quantitative prediction of the measured rates with no adjustable parameters when previously measured equilibrium values for step-step interactions and step wandering are used.