Growth and motion of liquid alloy droplets of Au on Ge(1 1 0)

Stenger, Bret; Dorsett, A.L.; Miller, J.H.; Russell, E.M.; Gabris, C.A.; Chiang, S.

doi:10.1016/j.ultramic.2017.05.005

Cited by 8 publications

(13 citation statements)

References 22 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: 59%

“…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: 59%

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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“…[19] for the motion of AuSi droplets on Si(111). In addition, it is noted that the obtained velocities of roughly 70-130 nm/s are right in the ballpark of literature values found for moving eutectic droplets on varies surfaces [4][5][6][8][9][10]19,20] and, further, that no distinct relation between the size and the velocity is observed. The latter is in line with several earlier reports too [4][5][6].…”

Section: Resultssupporting

confidence: 61%

“…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%

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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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Electron Tractor Beam: Deterministic Manipulation of Liquid Droplets on Solid Surfaces

Ukropcová

Dao

Štubian

et al. 2022

Adv Materials Inter

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The motion of liquid droplets is studied across many physics subfields and manipulation of nanoscale droplets on demand holds great promise in, e.g., nanotechnology. In this study, AuGe droplets on a germanium substrate are manipulated by an electron beam in a scanning electron microscope. The electron beam exposure creates a local temperature gradient in a substrate and induces a directional thermomigration of droplets nearby. To quantitatively analyse this phenomenon and to reveal the mechanism behind it, experimental observations under different conditions (beam current, sample temperature, scanning strategy) and simulations are combined. The obtained insights suggest that the droplet motion is limited by the dissolution of the substrate below the droplet. In addition, it is shown that the electron tractor beam is not only able to control the droplet motion but can also be used to split the droplets, thus opening new possibilities for droplet manipulation inside an SEM.

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Growth and motion of liquid alloy droplets of Au on Ge(1 1 0)

Cited by 8 publications

References 22 publications

Detailed characterization of supported eutectic droplets using photoemission electron microscopy

Detailed characterization of supported eutectic droplets using photoemission electron microscopy

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

Electron Tractor Beam: Deterministic Manipulation of Liquid Droplets on Solid Surfaces

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