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 Angstrom 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.