Morphological Instability of Steps During Crystal Growth from Solution Flow

TL;DR

This paper investigates the stability of steps during crystal growth from solution flow, revealing conditions under which steps become unstable or stable against various perturbations, influenced by flow intensity, step velocity, and line tension.

Contribution

It provides a detailed analysis of the conditions leading to step instability and stability during crystal growth from solution flow, including effects of flow intensity and step interactions.

Findings

Long-wavelength perturbations become unstable below a critical flow intensity.

Step velocity exceeding a critical value induces instability at given flow.

Step train with equal spacing remains stable against period variations.

Abstract

It is shown that step moving to meet solution flow can be unstable against lateral perturbations. The instability of long-wavelength perturbations occurs at values of the solution flow intensity less than some critical value depending on the step velocity. At given intensity of the solution flow, the instability comes at the step velocity exceeding a critical velocity. Decay of short-wavelength fluctuations is conditioned by the line tension of the step. The step moving along the solution flow is laterally stable at all values of the step velocity and the intensity of the solution flow. The overlapping diffusion field of the neighbour steps suppresses the lateral instability but it gives an instability of the step train against doubling of the period, i.e. neighbouring steps are attracted. The equidistant train moving to meet the solution flow is stable against the period variations.