The aim of this article is to compare the effects of adatom evaporation and ad-dimer diffusion on the growth of silicon structures on the Si(100)-2x1 surface in the range of 350-500 K. We study the results predicted by two models. Model A includes two types of evaporation (the breaking of ad-dimers and the detachment of single adatoms from islands) but excludes the diffusion of ad-dimers. Model B includes ad-dimer diffusion but no evaporation processes. We found that model A reproduces experimental findings much better than model B for fluxes greater than 6.75 x 10(-5) ML/s and doses lower than 0.1 ML. Indeed, ad-dimer diffusion seems to have no appreciable consequences on the final adatom structures. Also, the main experimental findings can be reproduced if the breaking of ad-dimers is removed from model A and only the detachment of single adatoms is allowed.