IMPURITY-INDUCED DIFFUSION BIAS IN EPITAXIAL-GROWTH

We introduce two models for the action of impurities in epitaxial grow th. In the first, the interaction between the diffusing adatoms and th e impurities is ''barrierlike'' and, in the second, it is ''traplike.' ' For the barrier model, we find a symmetry-breaking effect that leads to an overall downhill current. As expected, such a current produces Edwards-Wilkinson scaling. For the trap model, no symmetry breaking oc curs and the scaling behavior appears to be of the conserved Kardar-Pa risi-Zhang type.