Quantitative analysis of time-resolved RHEED during growth of vertical nanowires

Jakob, Julian; Schroth, Philipp; Feigl, Ludwig; Hauck, Daniel; Pietsch, U.; Baumbach, Tilo

doi:10.1039/c9nr09621c

Cited by 4 publications

(10 citation statements)

References 31 publications

(42 reference statements)

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“…The illumination efficiency γ(h,t ) takes NW ensemble-shadowing effects into account, which, in the case of strong absorption or extinction, have a significant influence on the diffracted intensity. 42 All functions within the integral are strongly affected by the growth dynamics and are, therefore, functions of the NW height h NW and growth time t.…”

Section: In Situ Rheed and Xrd By Nw Ensemblesmentioning

confidence: 99%

“…For RHEED, the much shorter electron extinction and absorption lengths compared to X-ray diffraction require the application of dynamical diffraction theory and give rise to self-shadowing phenomena within the individual NWs and ensemble-shadowing between different NWs 42 (see also Fig. 1).…”

Section: In Situ Rheed and Xrd By Nw Ensemblesmentioning

confidence: 99%

“…Therefore, Ω g (D(h,t ),Λ), becomes a function of the effective attenuation coefficient Λ, the diameter D and the geometrical shape of the NW cross-section, and of the azimuthal orientation of the NW shape with respect to the electron beam (details in ref. 42).…”

Section: In Situ Rheed and Xrd By Nw Ensemblesmentioning

confidence: 99%

“…For certain azimuthal orientations the RHEED signal may nearly completely disappear, although radial and axial growth may continue (ref. 42). Therefore, a favourable choice of the azimuthal orientation of the NWs in the electron beam is crucial.…”

Section: In Situ Rheed and Xrd By Nw Ensemblesmentioning

confidence: 99%

“…23,[36][37][38][39][40][41] Only recently, a quantitative evaluation procedure for in situ RHEED studies of NWs has been developed. 42 Based on a two beam approximation for dynamical Laue diffraction and taking shadowing effects within the NW ensembles into account, RHEED has been used for a time-resolved height-selective crystal phase analysis during NW growth. Similar to in situ XRD, it allowed representative quantitative information to be gained for large NW ensembles with several thousands NWs, but this required a priori assumptions considering the overall growth dynamics.…”

Section: Introductionmentioning

confidence: 99%

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Correlating in situ RHEED and XRD to study growth dynamics of polytypism in nanowires

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Section: In Situ Rheed and Xrd By Nw Ensemblesmentioning

confidence: 99%

Section: In Situ Rheed and Xrd By Nw Ensemblesmentioning

confidence: 99%

Section: In Situ Rheed and Xrd By Nw Ensemblesmentioning

confidence: 99%

Section: In Situ Rheed and Xrd By Nw Ensemblesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Correlating in situ RHEED and XRD to study growth dynamics of polytypism in nanowires

et al. 2021

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Metallic Transition Metal Dichalcogenides of Group VIB: Preparation, Stabilization, and Energy Applications

Wang

et al. 2021

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Layered transition metal dichalcogenides (TMDs) of group VIB have been widely used in the realms of energy storage and conversions. Along with the existence of semiconducting states, their metallic phases have recently attracted numerous attentions owing to their fascinating physical and chemical properties. Many efforts have been devoted to obtain metallic TMDs with high purity and yield. Nevertheless, such metallic phase is thermodynamically metastable and tends to convert into semiconducting phase, which necessitates the exploration over effective strategies to ensure the stability. In this review, typical fabrication routes are introduced and those critical factors during preparation are elaborately discussed. Moreover, the stabilized strategies are summarized with concrete examples highlighting the key mechanisms toward efficient stabilization. Finally, emerging energy applications are overviewed. This review presents comprehensive research status of metallic group VIB TMDs, aiming to facilitate further scientific investigations and promote future practical applications in the fields of energy storage and conversion.

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Insights into the Arsenic Shell Decapping Mechanisms in As/GaAs Nanowires by X-ray and Electron Microscopy

et al. 2021

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Nanowire heterostructures of the oxide (shell)–semiconducting (core) type are of interest for various applications in energy harvesting, such as electrodes for photocatalysis and in sensors. Their complete synthesis often requires the deposition of the shell and the core in two separate reactors, with the risk of exposing the core to oxidation from atmospheric conditions during transfer. Here, we study the desorption mechanisms and protection efficiency of an arsenic shell, which was purposely deposited on the GaAs core for protection against undesirable oxidation. Using in situ heating in transmission electron microscopy and synchrotron radiation scanning photoelectron microscopy, we explore the morphology, structure, and surface chemistry of GaAs nanowires capped with an arsenic shell, from room temperature to 500 °C. A phase transformation from amorphous to polycrystalline arsenic is evidenced at a temperature of about 300 °C, alongside the disappearance of the surface oxidation observed at room temperature. At higher temperatures, the arsenic shell desorbs with an activation energy of 2.32 eV, leading to clean facets. These results are helpful to determine pathways toward improving the efficiency of oxidation-protective layers on III–V semiconducting nanostructures.

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Quantitative analysis of time-resolved RHEED during growth of vertical nanowires

Abstract: In situ RHEED enables a height-resolved determination of the crystal structure of vertical nanowires via self-shadowing and ensemble shadowing.

Cited by 4 publications

References 31 publications

Correlating in situ RHEED and XRD to study growth dynamics of polytypism in nanowires

Correlating in situ RHEED and XRD to study growth dynamics of polytypism in nanowires

Metallic Transition Metal Dichalcogenides of Group VIB: Preparation, Stabilization, and Energy Applications

Insights into the Arsenic Shell Decapping Mechanisms in As/GaAs Nanowires by X-ray and Electron Microscopy

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