ROLE OF STEP AND TERRACE NUCLEATION IN HETEROEPITAXIAL GROWTH-MORPHOLOGY - GROWTH-KINETICS OF CAF2 SI(111)/

The thickness uniformity and the spatial distribution of lattice relax ation in thin (<8 nm) CaF2/Si(111) films, observed with photoelectron spectroscopy and transmission electron microscopy, are seen to depend strongly on the initial nucleation kinetics. We develop a general moda l for heteroepitaxial growth that explains both these and literature r esults. Terrace or step nucleation leads to laminar films, although wi th different relaxation patterns; combined step and terrace nucleation leads to rough films due to different upper-layer nucleation rates on the differently sized islands.