How Pb-overlayer islands move fast enough to self-assemble on Pb-Cu surface alloys.
Low-energy electron microscopy reveals that two-dimensional, approximately 50 000 atom, Pb-overlayer and vacancy islands both have diffusion coefficients of 25.6+/-0.8 nm2/sec at 400 degrees C on Pb-Cu surface alloys. This high mobility, key to self-assembly in this system, results from the fast transport of Pb atoms on the surface alloy and of Cu through the Pb overlayer. A high Pb vacancy concentration, predicted by ab initio calculations, facilitates the latter.
Anderson
M L
ML
Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
Bartelt
N C
NC
Feibelman
P J
PJ
Swartzentruber
B S
BS
Kellogg
G L
GL