Limited Rate of Fluctuations May Influence Crystal Growth Morphology

抄録

Growth hillocks and single steps were studied in situ by laser interferometry and atomic force microscopy on the (101) KDP face. The hillock is transformed from the rounded to the triangular, nearly fully polygonized, shape when the supersaturation rises. This indicates non-linear dependence of the average step rate for at least several step orientations. AFM studies of a single step though at much lower growth rate, showed that the roughening width of a step shrinks from 〜10μm at the step growth rate 0.14 nm /s to〜4μm at 7 nm/s. We believe both phenomenas occur because fluctuations are not fast enough to provide sufficient kink density. This is believed to happen because the rate at which fluctuations create kinks is finite and nearly supersaturation independent near equilibrium while the annihilation rate of kinks during growth increases with supersaturation. Examples concerning growth induced three dimensional faceting are mentioned.