SCALING ANALYSIS OF SURFACE-ROUGHNESS AND BRAGG OSCILLATION DECAY IN MODELS FOR LOW-TEMPERATURE EPITAXIAL-GROWTH

The structure of epitaxial thin films during growth is often probed experimentally up to only a dozen or so monolayers. Here we consider several models for low-temperature growth where thermal processes are inoperative. We find effective scaling of the interface width, W, of the form W2 approximately [h]2-beta or log [h], even in this experimentally relevant regime of small height [h]. This scaling behavior can be understood through consideration of the appropriate stochastic evolution equation for the coarse-grained film height. We emphasize physical interpretation of the terms in this equation which determine scaling, especially those reflecting lateral coupling due to realistic adsorption site geometries and deposition dynamics. Finally we consider how growth (or scaling) of W is reflected in the behavior of transient quantities such as Bragg intensity oscillations. We show that the envelope of these oscillations tends to decay like e-9.9W2 with increasing W. This provides a simple connection between W and the most commonly observed experimental quantity.