THE BACK-FORCE EFFECT IN THE MULTINUCLEATION GROWTH-PROCESSES

On the growth of the singular surface of the crystal, the surface diffusion process plays an important role. Since the adsorbed units on the growing surface are incorporated by the steps, the supersaturation on the surface is smaller than that in the environment. Such reduction of the surface supersaturation causes the reduction both of the advance velocity of steps and of the two-dimensional nucleation rate, and consequently the reduction of the growth rate. Those reductions are called the back-force effect. It is pointed out that the critical size of the two-dimensional nucleus on already existing nucleus is larger than the one on the flat surface due to the back-force effect. It may be called the effective critical radius. The theory of the multinucleation growth is formulated including the back-force effect and the growth rate is evaluated quantitatively. As a result, it is shown that the growth rate taking account of the back-force effect is smaller than the one derived from the conventional nucleation growth theory, especially in the range of high supersaturation. To confirm the validity of the back-force theory, computer simulations of the vapor growth of the perfect crystal are carried out by using Monte Carlo method. Good agreement is found between the back-force theory and the simulation results in wide range of the supersaturation. © 1990.