Instability of Liquid Cu Films on a SiO₂ Substrate

Abstract

We study the instability of nanometric Cu thin films on SiO2 substrates. The metal is melted by means of laser pulses for some tens of nanoseconds, and during the liquid lifetime, the free surface destabilizes, leading to the formation of holes at first and then in later stages of the instability to metal drops on the substrate. By analyzing the Fourier transforms of the SEM (scanning electron microscope) images obtained at different stages of the metal film evolution, we determine the emerging length scales at relevant stages of the instability development. The results are then discussed within the framework of a long-wave model. We find that the results may differ whether early or final stages of the instability are considered. On the basis of the interpretation of the experimental results, we discuss the influence of the parameters describing the interaction of the liquid metal with the solid substrate. By considering both the dependence of dominant length scales on the film thickness and the measured contact angle, we isolate a model which predicts well the trends found in the experimental data.

Instability of nanometric fluid films on a thermally conductive substrate

“…The price to pay is approximate nature of the results, in particular in the context of liquid metal films that are characterized by large contact angles and fast evolution that suggests that inertial effects (not included in the standard version of the long-wave framework considered here) may be relevant. However, despite the fact that all the assumptions involved in deriving long-wave approach are not strictly satisfied, one can obtain reasonably accurate results when using the long-wave approach to explain physical experiments -see, e.g., [17][18][19][20], or even when comparing to direct numerical solvers of Navier-Stokes equations [21].…”

“…where we use (n, m) = (3, 2) as motivated by direct comparison to the experimental results for Cu films [19]. Next, we define t s = 3µl s /γ 0 as the time scale, where l s is a chosen length-scale (we use typical film thickness of 10 nm).…”

“…The non-dimensional parameters are then specified by K = κl s /γ 0 , D = 3γ T /(2γ 0 ), and κ is related to Hamaker' s constant, A, by A = 6πκh 3 * l 3 s . The reader is referred to Appendix A for the values of the material parameters used, to [22] for extensive discussion regarding inclusion of disjoining pressure in the long-wave framework, to [15,17,19] for the use of the long-wave in the context of modeling liquid metal films, and to [1][2][3] for the discussion of Marangoni effects in a variety of settings. The numerical solutions of Eq.…”

“…The effect is particularly strong for thin films, that are strongly unstable due to destabilizing disjoining pressure, if Marangoni effect is excluded. The obvious question is whether these results are general, in particular in the light of experimental findings that find instability, see, e.g., [13,19]. To start answering this question, we consider the influence of two parameters: time dependence of the source term, and its total energy.…”

Dewetting dynamics of nickel thin film on alpha-quartz substrate: A molecular dynamics study

“…For example, metal nanoparticles monodispersed on the substrate are widely used as a catalyst of the synthesis of vertically-aligned carbon nanotubes [1][2][3]. Since size and density of nanoparticles strongly affect quality and yield of products [3], there are many studies focusing on the pattern formation and self-organization of metal nanoparticles on the substrate via the dewetting [4][5][6][7]. Moreover, dewetting is proactively used to synthesize various nanomaterials such as graphene-nanoribbon [8,9], nanowire [10] and nanoparticle-array [11,12].…”