Morphological Stability of a Linear Step in the Presence of a Mobile Adsorbed Impurity
As a growth front moves, concentration gradients form for an impurity (owing to its repulsion by the crystal) and the main substance (owing to its absorption by the crystal during growth from solution). These concentration gradients can cause the initially planar phase boundary to become unstable [1–3]. The random sinusoidal profile with time becomes more regular. The surface acquires a cellular (or macroscopically stepped ) structure. Movement of a linear step produces an analogous situation. Even if the medium (liquid or gaseous solution) is mixed well and is completely homogeneous, lateral concentration gradients due to surface diffusion of the main substance and impurities arise near the step. These lateral surface-concentration gradients can destabilize the linear step and produce a two-dimensional cellular structure.
KeywordsImpurity Concentration Kinetic Coefficient Growth Unit Instability Criterion Morphological Stability
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- 2.V. V. Voronkov, “Formation conditions of a cellular crystallization front,” Fiz. Tverd. Tela, 6, No. 10, 2984–2988 (1964).Google Scholar
- 4.V. V. Voronkov, “Motion of low-angle macrostep,” in: Growth of Crystals, Vol. 13, A. A. Chernov and G. I. Givargizov (eds.), Consultants Bureau, New York (1985), pp. 127–136.Google Scholar
- 6.C. Herring, “Surface tension as a motivation for sintering,” in: The Physics of Powder Metallurgy, McGraw-Hill, New York (1951), pp. 143–178.Google Scholar
- 7.A. A. Chernov, “Layered-spiral growth of crystals,” Usp. Fiz. Nauk, 73, No. 2, 277–331 (1961).Google Scholar
- 8.V. V. Voronkov, “Statistics of surfaces, steps and two-dimensional nuclei: A macroscopic approach,” in: Crystals: Growth, Properties, and Applications, Vol. 9, Springer, Berlin (1983), pp. 75–111.Google Scholar
- 10.P. Bennema and G. H. Gilmer, “Kinetics of crystal growth,” in: Crystal Growth: An Introduction, North Holland, Amsterdam (1973), pp. 263–327.Google Scholar
- 13.L. N. Rashkovich, KDP-Family Single Crystals, Adam Higler, Bristol (1991).Google Scholar
- 14.V. V. Voronkov and L. N. Rashkovich, “Influence of mobile adsorbed impurity on step kinetics,” Kristallografiya, 37, No. 3, 559–570 (1992).Google Scholar