A model that incorporates different atomic sticking parameters in the growing plane is proposed for the simulation of epitaxial growth of metastable semiconductor materials, and applied to (${A}^{\mathrm{III}{B}^{\mathrm{V}{)}_{1\mathrm{\ensuremath{-}}x}{C}_{2x}^{\mathrm{IV}}}}$ alloys. For this ternary system, two parameters completely specify the model, and are obtained from the experimental value of ${x}_{c}$, the critical composition at which the alloy undergoes a zinc-blende--diamond order-disorder transition. Differentiated sticking probabilities coupled to a kinetic growth model fully account for the experimentally measured long-range and short-range order-parameter variation with alloy composition. Any macroscopic probability associated with the formation of ${A}^{\mathrm{III}\mathrm{\ensuremath{-}}{A}^{\mathrm{III}}}$ and ${B}^{\mathrm{V}\mathrm{\ensuremath{-}}{B}^{\mathrm{V}}}$ bonds destroys the ordering of the alloy. The sticking probability between the group-IV element and group-III or -V elements is found to be about 60% of the sticking between ${C}^{\mathrm{IV}\mathrm{\ensuremath{-}}{C}^{\mathrm{IV}}}$ and ${A}^{\mathrm{III}\mathrm{\ensuremath{-}}{B}^{\mathrm{V}}}$ elements at the growing plane.