Step line tension and step morphological evolution on the Si(111) (1x1) surface

The temperature dependence of the step line tension on the Si (111) (1 x 1) surface is determined from a capillary wave analysis of two-dimensional island edge fluctuations and straight step fluctuations that are observed with low energy electron microscopy. The line tension decreases by nearly 20% with a linear temperature coefficient of -0.14 meV/angstrom K between 1145 and 1233 K. Temporal correlations of step fluctuations exhibit the distinctive signature in the wavelength dependence of the relaxation time of a terrace diffusion-limited mechanism for step motion. We also find that the role of desorption in island decay increases dramatically in the temperature range (1145-1380 K) that island decay is studied. Consequently, we generalize the current quasistatic model of island decay to take account of desorption. The evaluation of the island decay time with this model referenced to the temperature-dependent line tension accurately determines activation energies that are relevant to mass transport and sublimation.