MORPHOLOGY TRANSITION AND LAYER-BY-LAYER GROWTH OF RH(111)

We have observed a morphological transition in the nucleation and grow th of epitaxial Rh(111). The transition occurs near 600 K and is signa led by a change in the shape of the surface features from fingered to compact. The transition appears to be related to a change in the criti cal nucleation size. On both sides of the transition, there lies a reg ime of persistent layer-by-layer growth. The general surface features exhibit well-defined length scales and as growth proceeds they increas e in size following a power-law dependence on film thickness with a mo rphology-independent exponent of 0.33 +/- 0.03. The results suggest a general pathway to the layer-by-layer growth of close-packed metals.