FRISCH , Thomas

When a film is strained in two dimensions, it can relax by developing a corrugation in the third dimension. We review here the resulting morphological instability that occurs by surface diffusion, called the Asaro–Tiller–Grinfel'd instability (ATG), especially on the paradigmatic silicon/germanium system. The instability is dictated by the...

We put in evidence the unexpected behaviour of Leidenfrost droplets at the later stage of their evaporation. We predict and observe that, below a critical size $R_l$, the droplets spontaneously take-off due to the breakdown of the lubrication regime. We establish the theoretical relation between the droplet radius and its elevation. We predict...

We experimentally investigate the Leidenfrost effect at pressures ranging from $1$ to $0.05$ atmospheric pressure. As a direct consequence of the Clausius-Clapeyron phase diagram of water, the droplet temperature can be at ambient temperature in a non-sophisticated lab environment. Furthermore, the lifetime of the Leidenfrost droplet is...

Using molecular dynamic simulation, we study the stretching of an adsorbed homopolymer in a poor solvent with one end held at a distance $z_e$ from the substrate. We measure the vertical force $f$ on the end of the chain as a function of the extension $z_e$ and the substrate interaction energy $w$. The force reaches a plateau value at large...

International audience

We investigate the nucleation and growth of anisotropic and strained quantum dots in heteroepitaxy by means of kinetic Monte Carlo simulations. Surface energy anisotropy is introduced in order to depict Ge-like dots with (105) facets growing on a Si (100) substrate. Three dimensional islands, mainly in the form of square-base pyramids, are...

We perform numerical simulations of hexagonal quantum dots of AlGaN semiconductors. We show that the competition between surface mass diffusion and evaporation rules the morphology of the quantum dots. The system displays three different behaviors: presence of separated islands without a wetting layer, islands dissolving into the wetting layer,...

We study the influence of the growth kinetics on the Asaro-Tiller-Grinfel'd instability of a thin film deposited on a patterned substrate. We use a continuum model that we solve at first order in the surface slope. Both wetting interactions and elastic fields induced by the film/substrate interface introduce an explicit dependence on the film...

We studied the behaviors of Leidenfrost droplets confined in a Hele-Shaw cell. These droplets are unstable above a critical size and a hole grows at their center. We experimentally investigate two different systems for which the hole growth dynamics exhibits peculiar features that are driven by capillarity and inertia. We report a first regime...

We investigate the formation and the coarsening dynamics of islands in a strained epitaxial semiconductor film. These islands are commonly observed in thin films undergoing a morphological instability due to the presence of the elastocapillary effect. We first describe both analytically and numerically the formation of an equilibrium island...

In the framework of the lubrication approximation, we derive a set of equations describing the steady bottom profile of Leidenfrost drops coupled with the vapor pressure. This allows to derive scaling laws for the geometry of the concave bubble encapsulated between the drop and the hot plate under it. The results agree with experimental...

We investigate the morphological evolution of SiGe quantum dots deposited on Si( 100) during longtime annealing. At low strain, the dots' self-organization begins by an instability and interrupts when (105) pyramids form. This evolution and the resulting island density are quantified by molecular-beam epitaxy. A kinetic model accounting for...

International audience

We experimentally and theoretically investigate the behavior of Leidenfrost droplets inserted in a Hele-Shaw cell. As a result of the confinement from the two surfaces, the droplet has the shape of a flattened disc and is thermally isolated from the surface by the two evaporating vapor layers. An analysis of the evaporation rate using simple...

We experimentally and theoretically investigate the behavior of Leidenfrost droplets inserted in a Hele-Shaw cell. As a result of the confinement from the two surfaces, the droplet has the shape of a flattened disc and is thermally isolated from the surface by the two evaporating vapor layers. An analysis of the evaporation rate using simple...

Strained epitaxial SiGe on vicinal Si(001) substrates develops a morphological instability perpendicular to the steps unlike the usual growth instabilities on vicinal substrates, eventually leading to planar nanowires. We assess both theoretically and experimentally the effect of strain anisotropy on the 1D elongation of the...

International audience

International audience

We exhibit both experimentally and theoretically a novel growth mode for the epi-taxy of AlGaN quantum dots (QD), where they are eventually produced without their usual surrounding wetting layer. If the generic evolution of QD is ruled by the elastic relaxation and capillary effects, evaporation occurs here on a time scale similar to that of...