Atomic Transport in Au-Ge Droplets: Brownian and Electromigration Dynamics

Leroy, F.; Barraj, Ali El; Cheynis, Fabien; Müller, Pierre; Curiotto, S.

doi:10.1103/physrevlett.123.176101

Cited by 13 publications

(9 citation statements)

References 47 publications

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“…Droplet 1 is at the local hot spot and is, thus, fully in equilibrium, whereas the other droplets are on their way to the hot spot. Such motion in the direction of the highest temperature has also been observed for the similar eutectic systems [4][5][6][7][8][9][10]. In the following sections we discuss important characteristics of the morphology of the eutectic PtGe droplets as revealed by PEEM.…”

Section: Resultssupporting

confidence: 60%

“…Applications involve the growth of the two-dimensional material germanene [2] or standing-up Si nanowires [3] from the eutectic dropletx. Several of these eutectic systems have been studied by surface electron microscopy [4][5][6][7][8][9][10]. Information on the three-dimensional (3D) details of these liquid droplets, however, is rarely obtained from electron microscopy [11,12].…”

Section: Introductionmentioning

confidence: 99%

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Detailed characterization of supported eutectic droplets using photoemission electron microscopy

Zhang

Poelsema

Zandvliet

et al. 2021

Phys. Rev. Materials

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Pt-Ge eutectic alloy droplets are scrutinized by microscopic analysis of electrons excited by 4.9-eV photons. Using only the work function and contact angle as fitting parameters, we determine the exact droplet shape that reproduces the experimental electron emission profile. The local inclination of the droplets' surface plays a decisive role in the generated emission profile. Intensity variations at the illuminated side of the eutectic droplets are a consequence of standing waves in the electromagnetic field responsible for excitation. Intensity variations at the nonilluminated side are ascribed to a diffraction pattern of the photons after their interaction with the droplet.

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Section: Resultssupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Detailed characterization of supported eutectic droplets using photoemission electron microscopy

Zhang

Poelsema

Zandvliet

et al. 2021

Phys. Rev. Materials

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“…Also under EM when the Au ux is stopped the droplets stop moving. It could have been envisaged that the EM force is sucient to make droplets move, as observed in other systems [25,39]. However, as only during Au deposition the droplets move, we conrm the importance of the substrate dissolution in the observed mechanisms.…”

Section: Comparison With Results Without Emsupporting

confidence: 71%

“…kT , where F is the electric eld force, D the droplet diusion coecient, k the Boltzmann constant and T the temperature) [5,34]. As theoretically expected [37,38] and experimentally shown [39], the diusivity of a nanostructure decreases when its volume increases. Therefore, considering the results of gure 9, it would be tempting to use the Nernst-Einstein equation to describe the droplet motion.…”

Section: Mechanism Of Motion In Presence Of Emmentioning

confidence: 63%

Mechanism of droplet motion and in-plane nanowire formation with and without electromigration

Curiotto

Müller

Cheynis

et al. 2022

Applied Surface Science

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

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“…Considerable attention has been paid to the dynamics of metallic droplets on surfaces since then. This includes the motion of Ga droplets on GaAs under incongruent evaporation conditions [2,3], thermomigration of PtSi droplets on stepped Si(111) and Si(100) [4][5][6], AuSi-and AuGe-droplets on various Si and Ge substrates [7,8], AuGe on Ge(110) [9], and, recently, electromigration of AuGe [10]. The surface studies were motivated by interest in possibilities for bottom-up fabrication of nanostructures, catalysis of standing up [11] and lying down nanowires [12,13] on surfaces, and, last but not least, genuine interest in the complex physics of the motion of metallic droplets on surfaces.…”

Section: Introductionmentioning

confidence: 99%

Shining new light on the motion of eutectic droplets across surfaces: A PEEM study of PtGe on Ge(110)

Poelsema

Zhang

Solomon

et al. 2021

Phys. Rev. Materials

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Thermally stimulated motion of micron-sized eutectic PtGe droplets on Ge(110) has been studied in situ mainly by photoemission electron microscopy, low-energy electron microscopy, and spatially resolved lowenergy electron diffraction. In line with earlier studies of eutectic AuSi, PtSi, AuGe, and PtGe clusters on, respectively, various Si and Ge substrates we find that the motion toward regions at higher temperature is driven by the entropy gain of substrate atoms which become constituents of the droplet during its journey. At ∼1100 K, i.e., well above the bulk eutectic temperature, the direction is governed solely by the local thermal gradient, irrespective of eventual crystalline preferences. Access to the diffusivity of the host material (in this case Ge) inside the eutectic droplets shows that this is well above one order of magnitude higher than expected if it was rate limiting for the velocity of the moving droplets. This excludes a significant gradient of the (Ge) concentration inside the droplet and disqualifies dissolution-diffusion-deposition flow as the driving force for motion of the droplets on the surface, as assumed widely hitherto, to explain surface diffusion of eutectic droplets on surfaces. In addition, the interface between the droplet and the surface appears flat and we find no indication for "endotaxy." The droplets make direct contact with the flat Ge substrate through atomic steps, which are abundantly present at the interface. The droplets are surrounded by a PtGe 3 wetting layer with an ordered (2 × 1) structure. Dissolution of the edges of the wetting layer at the leading edge of the droplet with an activation energy of 2.2 eV is identified as the rate limiting step for its motion.

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Atomic Transport in Au-Ge Droplets: Brownian and Electromigration Dynamics

Cited by 13 publications

References 47 publications

Detailed characterization of supported eutectic droplets using photoemission electron microscopy

Detailed characterization of supported eutectic droplets using photoemission electron microscopy

Mechanism of droplet motion and in-plane nanowire formation with and without electromigration

Shining new light on the motion of eutectic droplets across surfaces: A PEEM study of PtGe on Ge(110)

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