Asymmetric coalescence of reactively wetting droplets

Zheng, Changxi; Tang, Wing Man; Jesson, D. E.

doi:10.1063/1.3684616

Cited by 17 publications

(9 citation statements)

References 25 publications

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“…The observed depressions are surrounded by GaAs ringlike structures whose diameter is similar to that of the corresponding Ga droplet. A similar phenomenology was observed in Ga droplets formed at T S = 350°C [ 6 ] and in ten times larger Ga droplets created by annealing a GaAs(001) substrate at 670°C, above the surface congruent evaporation temperature [ 27 ].…”

Section: Resultssupporting

confidence: 54%

Fundamental role of arsenic flux in nanohole formation by Ga droplet etching on GaAs(001)

Fuster¹,

González²,

González³

2014

Nanoscale Res Lett

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Nanoholes with a depth in the range of tens of nanometers can be formed on GaAs(001) surfaces at a temperature of 500°C by local etching after Ga droplet formation. In this work, we demonstrate that the local etching or nanodrilling process starts when the Ga droplets are exposed to arsenic. The essential role of arsenic in nanohole formation is demonstrated sequentially, from the initial Ga droplets to the final stage consisting of nanoholes surrounded by ringlike structures at the surface and Ga droplets consumed. The kinetics of local etching depends on the arsenic flux intensity, while the ringlike structures are basically the same as those formed underneath the droplets in the absence of arsenic. These structures show motifs with well-defined crystalline facets that correspond to those expected from surface energy minimization. These experimental results are qualitatively analyzed for a better understanding of the nanohole formation underlying processes.

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Section: Resultssupporting

confidence: 54%

Fundamental role of arsenic flux in nanohole formation by Ga droplet etching on GaAs(001)

Fuster¹,

González²,

González³

2014

Nanoscale Res Lett

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“…Indeed, as shown by Somanchini et al [11], such edge growth occurs even before As is turned on. A similar preexisting ridge was also found to occur beneath droplets prepared by annealing [25]. In both cases the preexisting ridge is small compared to the subsequent inner ring growth, so here we neglect any ridge growth that occurs prior to the As flux.…”

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confidence: 70%

Origin of Quantum Ring Formation During Droplet Epitaxy

et al. 2013

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Droplet epitaxy of GaAs is studied in real time using in situ surface electron microscopy. The resulting movies motivate a theoretical model for quantum ring formation which can explain the origin of nanoscale features such as double rings observed under a variety of experimental conditions. Inner rings correspond to GaAs deposition at the droplet edge, while outer rings result from the reaction of Ga and As atoms diffusing along the surface. The observed variety of morphologies primarily reflects relative changes in the outer rings with temperature and As flux.

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“…47,48,50 As a consequence, Ga-rich droplets stem from clustering and coalescence of the accumulating Ga-rich GaGe on the growing surface of the Ge-rich GaGe thin films. 51,52 It is worth noting that the Ga compositions of 5.2-5.8 at% as probed by EDX in the epitaxial GaGe thin films are much larger than the solid solubility of Ga in Ge (1.1 at%). 40 This is not surprising since the solid solubility was determined in a thermodynamic equilibrium state of the alloy while the thin films studied here were deposited in a metastable situation, which is far from the thermal equilibrium state.…”

Section: Resultsmentioning

confidence: 99%

Droplet-induced dot, dot-in-hole, and hole structures in GaGe thin films grown by MOCVD on GaAs substrates

2016

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We report observations and origins of Ga-rich GaGe droplets and the localized etching of Ge-rich GaGe thin films grown on GaAs (100) substrates by metalorganic chemical vapor deposition. Micron and sub-micron dots, dot-in-holes, and holes have been fabricated by controlling the partial pressures of the Ga and Ge precursors as well as the substrate temperatures. The dot-in-hole features can also be converted to empty holes via post-growth sonication in hot deionized water due to the low melting point of the Ga-rich dots. Enhanced Raman scattering (ERS) of the Ge-Ge lattice vibrational mode has been observed at the wall of the concentric dot-in-hole structures as well as in the empty holes. To interpret the ERS mechanism, we have carried out finite-difference time-domain (FDTD) simulations, which reveal an enhanced electrical field for the obtained structures as a result of interference between the incident and reflected waves at the surface of the thin films that, in turn, results in the observed ERS. These findings greatly enrich the conventional droplet epitaxy and etching techniques and widen their applications.

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Asymmetric coalescence of reactively wetting droplets

Cited by 17 publications

References 25 publications

Fundamental role of arsenic flux in nanohole formation by Ga droplet etching on GaAs(001)

Fundamental role of arsenic flux in nanohole formation by Ga droplet etching on GaAs(001)

Origin of Quantum Ring Formation During Droplet Epitaxy

Droplet-induced dot, dot-in-hole, and hole structures in GaGe thin films grown by MOCVD on GaAs substrates

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