11:45 AM - 12:00 PM
[MIS10-10] Crystal growth hysteresis in birth-and-spread mechanism
Keywords:Crystal growth, Step dynamics, Impurity effect, Phase-field method
The mechanism of the crystal growth hysteresis was elucidated by a mean field theory. Punin & Artamonova  and Miura & Tsukamoto  formulated the following two effects —inhibition of step advancement by adsorbed impurities (pinning effect) and removal of adsorbed impurities by step passages (impurity sweeping)— to clarify the existence of multiple steady solutions that satisfies both of two formulas at a certain range of supersaturation. In the case of constant step interval, numerical simulations based on a phase-field method demonstrated that the growth hysteresis emerges as predicted by the mean field theory even when the physical quantities are fluctuated around these averages . The phase-field simulations also confirmed the emergence of hysteresis in the case that the surface is grown by a screw dislocation . However, the growth hysteresis has not been investigated in the case that the surface is grown by two-dimensional nucleation (birth-and-spread mechanism), which is another mechanism to generate new steps on the surface. The birth-and-spread growth dominates the spiral growth at high supersaturation, so it is important to elucidate the impurity-induced effect for that. In this study, we theoretically investigate the growth hysteresis in the birth-and-spread growth mechanism.
At first, we formulated the interdependence between the step velocity and the amount of adsorbed impurities based on the mean field theory, in the same way in the case of the spiral growth. As the result, we found that multiple steady solutions exist at a certain range of supersaturation. This suggests that the growth hysteresis can emerge even in the birth-and-spread growth in principle. At second, we carried out the phase-field calculation with the equivalent condition of the mean field theory. We confirmed the emergence of growth hysteresis in down-and-up cycles of supersaturation. In addition, we found that the range in supersaturation at which the growth hysteresis is observed depends on the rate of supersaturation variation: slow change in supersaturation makes the hysteresis behavior unclear.
 Y. O. Punin and O. I. Artamonova, Kristallographiya 32, 1262 (1989).  H. Miura and K. Tsukamoto, Cryst. Growth Des. 13, 3588 (2013).  H. Miura, Cryst. Growth Des. 16, 2033 (2016).  H. Miura, JpGU-AGU Joint Meeting 2017, abstract MIS11-P04.