1998 年 15 巻 1 号 p. 2-
Crystal growth rate of a dislocation-free crystal was measured accurately in microgravity by means of a newly developed technique, Real-Time Phase-Shift Interferometry (RPS!), which is two-order of magnitude more sensitive than conventional interferometry. The crystal was grown to a thickness of 200 nm on the (100) face of the dislocation-free seed crystal during the continuous cooling from 31 to 25°C for 6 min. The crystal did not grow till the supersaturation of the solution reached 3%. This is in contrast to the growth in Earth's gravity, in which heterogeneous 2D nucleation operates below that critical supersaturation. It was observed for the first time that, even in microgravity, the growth rate does not monotonously increases with increasing bulk supersaturation but goes through a distinct minimum because of a relaxation process of the surface supersaturation. This growth rate fluctuation was analyzed by solving a one-dimensional time-dependent diffusion equation that accounts for surface kinetic processes. It was shown analytically that this fluctuation is expected when temperature was continuously decreased and the crystal suddenly started to grow.
