Journal of Vacuum Science & Technology B: Microelectronics and
Nanometer Structures -- July 1996 -- Volume 14, Issue 4,
pp. 2799-2808
Relaxation of the step profile for different microscopic
mechanisms
Da-Jiang Liu, Elain S. Fu, M. D. Johnson, John D. Weeks, and Ellen
D. Williams
Abstract:
Theoretical and experimental studies of the rate of decay of
metastable structures are compared quantitatively. The effect of
decay mechanism, size and periodicity of the structure on the rate
of decay is evaluated within both a coarse-grained step-based model
and a continuum model. For high-amplitude structures, the decay
scales with size N and time as (t/N
)-
.
The exponents
and
depend on the mass transport mechanism. The size-scaling is
=4 for locally conserved diffusive flux and
=2 for
locally non-conserved flux. The time scaling exponent is
=1/5 for
diffusive limited mass transport and
=1/4 for
step attachment limited mass transport. Experiments were performed
on metastable structures of controlled sizes 3-5 nm in height,
prepared by direct current heating on Si(111). Quantitative
agreement with theoretical predictions of both scaling (
=4.3 +-
0.5,
=0.2-0.3)
and absolute rate of decay were obtained.