Thermal roughening of a thin film: A new type of roughening transition
The equilibrium thermal roughening of thin Ge layers (one and two monolayers) deposited on Si(001) has been investigated with low-energy electron microscopy. A Ge-coverage-dependent roughening is observed. For two monolayers, the temperature at which imaging contrast is lost due to surface roughness is 900+/-25 degrees C, between the roughening temperatures of Ge(001) and Si(001). Lower Ge coverages move this temperature closer to that of Si(001). The roughening is confined to the Ge overlayers. It is believed that this phenomenon represents a new type of surface roughening transition that should be generally applicable for heteroepitaxial films.
Maxson
JB
University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Savage
DE
Liu
F
Tromp
RM
Reuter
MC
Lagally
MG