SURFACE-DIFFUSION CURRENTS AND THE UNIVERSALITY CLASSES OF GROWTH

We show, through simulations of a variety of one- and two-dimensional solid-on-solid models, that nonequilibrium surface diffusion processes in the presence of a deposition flux are generically characterized by a nonvanishing inclination-dependent mass current along the surface. The current stabilizes the surface, leading to Edwards-Wilkinson scali ng for the surface fluctuations, if it is a decreasing function of inc lination, but induces a growth instability otherwise. Both types of be havior generally occur for the same system at different surface orient ations.