Surface Processes at the Nanoscale: how crystals meet the outside world
John A. Venables
Department of Physics, Arizona State University, Tempe, Arizona 85287-1504
ABSTRACT
Starting with the example of snowflakes, we can see how crystal growth has
fascinated generations of artists and scientists alike. Nowadays, crystal growth, and
more generally “surface processes at the nanoscale” is central to many technologies,
based on non-equilibrium rate, diffusion and reaction processes at surfaces.
Nucleation and growth models using rate and rate-diffusion equations are well
developed for nucleation and growth on homogeneous substrates. This topic is
reviewed briefly.
However, these models have needed further development to cope with nucleation on
defects, general non-homogenous substrates and time-varying diffusion fields. The
physical context is set by the importance of both attractive and repulsive interactions
in the nucleation and growth of many nanostructures, e.g. metal nanoclusters, hut
clusters and nanowires. To address this need, rate equation models of defect
nucleation have been developed, and the general time-dependent problem of
adparticle diffusion and crystal growth in a two-dimensional potential field has been
solved on a lattice. Examples are given to compare with selected nanoscale
experiments on Ti/Si(001), Pd/MgO(001), Cu/Cu(111) and Ge/Si(001), and are
illustrated by Matlab® programs and movies.