Kinetics of atomic-scale fluctuations of steps on Si (001) measured with variable-temperature STM

Using a variable-temperature scanning tunneling microscope (STM) we measure the time evolution of the atomic-scale morphology of steps on Si(001) in equilibrium at temperatures up to 350°C. At temperatures above 230°C, local changes in the atomic arrangement of the steps are observed between successive STM images. The relative rate at which events occur depends on the local configuration of the step. Rearrangement events are more likely to occur at kink sites than at straight sections of the step. The relative rates at which the rearrangement events occur are determined by the configuration energy of the steps as expected from detailed balance. By measuring the event rate as a function of temperature we determine the effective activation energy barrier for step rearrangement, 1.3 ± 0.3 eV. © 1995.