The growth of highly lattice-mismatched InAs 0.3 Sb 0.7 films on (100) GaAs substrates by magnetron sputtering has been investigated and even epitaxial InAs 0.3 Sb 0.7 films have been successfully obtained. A strong effect of the growth conditions on the film structure was observed, revealing that there was a growth mechanism transition from three-dimensional nucleation growth to epitaxial layer-by-layer growth mode when increasing the substrate temperature. A qualitative explanation for that transition was proposed and the critical conditions for the epitaxial layer-by-layer growth mode were also discussed.