Computer simulations of mogration-enhanced epitaxial growth are used to obtain time dependences of the Ga As film average height and roughnedd under different growth conditions. It is shown that the average height vs time function is linearly stepwise and time dependences of roughness are oscillating in nature. It is found thax the roughness may be 1,5-2 times reduced as compared to the molecular-beam eputaxy technique at optimal growth conditions.