Multilayer thin film growth on crystalline and quasicrystalline surfaces: A phase-field crystal study

Abstract

In this paper, we explore the effects of misfit strain fields on both heterogeneous nucleation behavior and anisotropic growth of islands at submonolayer coverages and compositional patterning at complete monolayer coverage via simulations of a phase-field crystal model. In particular, deposition on top of a herringbone structure and quasicrystalline (QC) substrate are considered, the former representing a system with spatially periodic misfit strain fields arising from the presence of surface dislocations, while the latter representing a system which inherently possesses a wide range of local, aperiodic misfit patterns. In the case of single component systems, we demonstrate that misfit strain fields lead to heterogeneous nucleation behavior and anisotropic island growth. In the case of QC substrate, a wide range of morphologies, such as coexistence of locally hexagonally ordered atomic clusters within a larger scale arrangement with overall QC symmetry and so-called "starfish" aggregates, is observed in pure system at sub-monolayer coverages when the adlayer-substrate interaction strength and lattice mismatch are tuned. In the case of bulk-immiscible binary systems at complete monolayer coverage, strain-stabilized compositional domains emerge at low line tension values for both substrates. Interestingly, the compositional domains on the QC substrate inherit their symmetries at sufficiently low line tension values, while at larger line tension values, the domain structure begins to resemble the classical spinodal microstructure. Such domain structures should be readily observable in colloidal systems in which attractive inter-particle and particle-substrate interactions can be tuned.

Modeling self-organization of thin strained metallic overlayers from atomic to micron scales

“…This approach has been used to describe commensurateincommensurate transitions, 34,39 sliding friction, 40,41 and the ordering of ultrathin binary films. 35,36 All lengths are scaled such that the fundamental length scale is a f /2π and the amplitude of the coupling potential V 0 is also written in dimensionless form, whose relevance to experimental systems will be discussed in the following. The resulting equation of motion for the amplitudes, as done by Goldenfeld et al 28,29 and others, [30][31][32] is…”

Stochastic simulation of nucleation in binary alloys

“…where A k are the constant coefficients º ( ) In a general case, simulation of the random field with correlation function (9) can be executed by the approach developed in [34] (see also, [35][36][37]), which can also be applied for the case of variable mobility. In the considered case of constant mobility one can simulate the random variables x ¢ ˆk directly.…”

“…The approach of noise simulation has a very important restriction related to atomic structure of the alloy. The discrete structure is usually associated with wave vector cutoff [17,36], assuming all amplitudes [36]). The cutoff wave vector k , max can also be related to the correlation length [17] commonly discussed in linearized theory of spinodal decomposition [5,31].…”

Morphology of monolayer films on quasicrystalline surfaces from the phase field crystal model

“…We find several distinct phases that depend on the detailed nature of adsorption sites and the strength of surface/monolayer couplings. Here we focus on complete monolayer coveragethe submonolayer regime will be discussed elsewhere [18]. We also grow a surface with seven-fold symmetry and show that quasicrystalline films on this surface form only for much stronger surface/monolayer interactions than on the five-fold substrate.…”