Dynamic Interaction of Steps and Nanoislands during Growth of a Multicomponent Crystal

Abstract

Processes of formation of islands of individual components on terraces during step-flow growth of a multicomponent crystal are considered. This phenomenon is observed repeatedly in experiments and is possible when an excess of one of the components accumulates on the surface. In this case, multicomponent steps can be used as an additional tool to control the ensemble of islands on the crystal surface because, unlike single-component systems, it is possible to independently control the motion of the steps and the kinetics of the growth of one-component islands. Analytical criteria are obtained for identifying the conditions under which the nucleation of islands of individual components is possible. The interaction of an individual island and a step on the surface of a multicomponent crystal is investigated. A mechanism of dynamically stable forming quasiperiodic layers of islands is discussed. Under certain conditions, the observed phenomena can be used for the bottom-up formation of various quasi-ordered nanostructures both on the surface and in the bulk of the growing crystal.

Theoretical aspects of the growth of a non-Kossel crystal from vapours: the role of advacancies

“…Let us use the conditions of the experiment, 62 at which the MBE growth of GaN was performed at a temperature of 730 °C. The equilibrium concentration of the gallium adatoms at the surface thus can be estimated 33 as n 0 aGa = 4 × 10 7 at cm −2 , the lifetime of the adatoms 63 equals τ aGa ∼ 10 −7 s, and their diffusion coefficient is D Ga ∼ 2 × 10 −8 m 2 s −1 . The diffusion length due to evaporation can then be estimated as .…”

“…We should know the equilibrium surface concentrations of Ga adatoms n 0 aGa and vacancies n 0 vGa and their lifetimes. Let us use the conditions of the experiment, 62 at which the MBE growth of GaN was performed at a temperature of 730 C. The equilibrium concentration of the gallium adatoms at the surface thus can be estimated 33 as n 0 aGa ¼ 4 Â 10 7 at cm À2 , the lifetime of the adatoms 63 equals s aGa $ 10 À7 s, and their diffusion coefficient is D Ga $ 2 Â 10 À8 m 2 s À1 . The diffusion length due to evaporation can then be estimated as l e Ga ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi D Ga s aGa p $ 45 nm.…”

“…30 However, although the single-component analytical models describe multicomponent systems well in certain cases, 31 it is obvious that the latter demonstrate some peculiarities and effects caused by the presence of several components. 32,33 Thus, the properties of each component (diffusion coefficients, equilibrium concentration, etc. ) should be considered to accurately describe the general growth process.…”

Spiral growth of multicomponent crystals: theoretical aspects

“…In (Redkov and Kukushkin, 2020), the authors demonstrated that nucleation of islands consisting of pure components on the terraces between the steps is possible during step-flow growth, similar to the process of dew formation (refer to Figure 2A). In a subsequent study (Redkov and Kukushkin, 2021), it was shown that the precipitation of such islands can significantly impact the growth process, resulting in the formation of undesirable defects and inclusions in the crystal, and even cause different types of morphological instability (Bales and Zangwill, 1990). This phenomenon may occur when the surface concentration n ai (x) of a particular component on the surface between the steps exceeds the equilibrium single-component concentration n 0 ai (x) required for nucleation.…”

Influence of Adatoms on the Vacancy Growth of Faceted Pores in a Crystal Under Mechanical Load

“…Since the process of growth of an ordinary crystal and a pore are similar, similarly to the effect of advacancies on the growth of a crystal, adatoms on the surface of a pore can affect the rate of its vacancy growth. This work is a continuation of a series of works devoted to the growth and evolution of crystals [11][12][13][25][26][27][28] and pores in single-and multicomponent systems due to various mechanisms, and its main goal is to analyze the effect of adatoms on the pore surface on its vacancy growth of the pore according to the Barton-Cabrera-Frank mechanism, and find an expression for the dependence of the pore growth rate on the applied mechanical load and the properties of the crystal.…”