  We examine the step dynamics in a 1+1 dimensional model of epitaxial growth
based on the BCF-theory. The model takes analytically into account the
diffusion of adatoms, an incorporation mechanism and an Ehrlich-Schwoebel
barrier at step edges. We find that the formation of mounds with a stable slope
is closely related to the presence of an incorporation mechanism. We confirm
this finding using a Solid-On-Solid model in 2+1 dimensions. In the case of an
infinite step edge barrier we are able to calculate the saturation profile
analytically. Without incorporation but with inclusion of desorption and
detachment we find a critical flux for instable growth but no slope selection.
In particular, we show that the temperature dependence of the selected slope is
solely determined by the Ehrlich-Schwoebel barrier which opens a new
possibility in order to measure this fundamental barrier in experiments.
