PHASE-SEPARATION IN A SINGLE-STEP GROWTH-MODEL WITH SURFACE-DIFFUSION

We consider a one-dimensional solid-on-solid growth model in which the nearest-neighbour height differences are restricted to take the value s +/-1. Deposition occurs at local minima with probability f, while di ffusion moves of single adatoms within a layer occur with probability 1-f. Interlayer transport and detachment from step edges is suppressed . For f --> 1 the stationary distribution of the model is known, hence the growth-induced surface current can be computed analytically for s mall diffusion rates. In the opposite, diffusion-dominated limit, f -- > 0, a description in terms of step flow is possible for slopes larger than a critical slope u(c). For smaller slopes the surface phase sepa rates into regions of slope +/-u(c). The stationary domain size diverg es for f --> 0 as f(-v), where v approximate to 0.5. We suggest that t he large-scale behaviour in this limit can be described by the noisy K uramoto-Sivashinsky equation in its noise-dominated regime.