Core-Shell Germanium/Germanium–Tin Nanowires Exhibiting Room-Temperature Direct- and Indirect-Gap Photoluminescence

Meng, Andrew C.; Fenrich, Colleen S.; Braun, Michael; McVittie, J.P.; Marshall, A. F.; Harris, James S.; McIntyre, Paul C.

doi:10.1021/acs.nanolett.6b03316

Cited by 65 publications

(58 citation statements)

References 38 publications

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“…Unfortunately, Sn incorporation in the nanowires is much more difficult to achieve with this technique, thus explaining the small amount of studies about GeSn nanowires grown by CVD‐VLS process. Two research groups managed to create Ge/GeSn core‐shell nanowires by making a 2D growth around Ge nanowires and one group has elaborated GeSn nanowires using a liquid‐injection CVD technique via the VLS mechanism with metal alloys catalysts and Diphenylgermane and Allyltributylstannane as precursors …”

Section: Introductionmentioning

confidence: 99%

Growth of Ge_1−xSn_x Nanowires by Chemical Vapor Deposition via Vapor–Liquid–Solid Mechanism Using GeH₄ and SnCl₄

Haffner

Zeghouane

Bassani

et al. 2017

Physica Status Solidi (a)

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In this work we report on the elaboration and characterization of Ge1−xSnx nanowires synthetized by chemical vapor deposition (CVD) via vapor–liquid–solid (VLS) mechanism using GeH4 and SnCl4 as precursors. We have investigated tin incorporation in Ge as a function of experimental growth conditions such as growth temperature and Sn precursor partial pressure (PSnCl4/PGeH4 ratio). We have demonstrated Ge1−xSnx nanowires with Sn incorporation around 1 at.% in the core with a thin Sn‐rich shell with up to 10 at.% Sn well beyond the equilibrium solubility of Sn in bulk Ge.

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Section: Introductionmentioning

confidence: 99%

Growth of Ge_1−xSn_x Nanowires by Chemical Vapor Deposition via Vapor–Liquid–Solid Mechanism Using GeH₄ and SnCl₄

Haffner

Zeghouane

Bassani

et al. 2017

Physica Status Solidi (a)

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“…The Sn content is mapped by colors and its radial variation along both <112> and It is worth noticing that in the present work the systematic analysis of shape and composition was focused on samples with 100nm cores, quite large compared to the ones typically discussed in literature. [12][13][14]32 This was essential in order to hove dodecagonal shapes including {110} facets. Indeed, in all other samples with smaller core radius (down to 50 nm) only a {112}bounded hexagonal cross-section was observed for all Ge/Sn ratio (unless irregular, defected shapes where obtained).…”

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confidence: 99%

Kinetic Control of Morphology and Composition in Ge/GeSn Core/Shell Nanowires

et al. 2020

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The growth of Sn-rich group-IV semiconductors at the nanoscale provides new paths for understanding the fundamental properties of metastable GeSn alloys. Here, we demonstrate the effect of the growth conditions on the morphology and composition of Ge/GeSn core/shell nanowires by correlating the experimental observations with a theoretically developed multi-scale approach. We show that the cross-sectional morphology of Ge/GeSn core/shell nanowires changes from hexagonal (bounded by {112} facets) to dodecagonal (bounded by both {112} and {110} facets) upon increasing the supply of the Sn precursor. This transformation strongly influences the Sn distribution as a higher Sn content is measured under {112} facets. Ab-initio DFT calculations provide an atomic-scale explanation by showing that Sn incorporation is favored at the {112} surfaces, where the Ge bonds are tensile-strained. A phase-field continuum model was developed to reproduce the morphological transformation and the Sn distribution within the wire, shedding light on the complex growth mechanism and unveiling the relation between segregation and faceting.pulling during the shell growth. 14 However, at larger core diameters the shell will experience higher strain, eventually inducing plastic deformation with the nucleation of defects and surface roughening. 18,19 In this work, we show how the morphology and composition of the GeSn shell on a Ge core NW are strongly dependent on the growth conditions. At a higher supply of the Tintetrachloride (SnCl4) precursor, the symmetry of the NW cross-section changes from 6-fold to 12-fold by increasing the size of the six {110} (corner) facets in the GeSn shell with respect to the (main) six {112} facets. At the same time, enhanced segregation is observed, with an increasing difference in composition between Sn-poor <110>-oriented stripes and Sn-rich {112}oriented facets. In addition, at the highest supply of the Sn precursor, phase separation occurs and multiple Sn droplets are visible on the NW sidewall. The experimental observations are then rationalized theoretically by a multi-scale approach. First, the shape transition will be interpreted by a continuum kinetic growth model, including surface diffusion. Then, first principle calculations will be exploited to assess the origin of the different composition within the facets and to extend the growth model in order to simultaneously trace the evolution of shape and composition. The agreement between experiments and theory highlights the strong correlation between faceting and segregation dynamics in the Ge/GeSn core/shell NW system. RESULTS AND DISCUSSIONExperimental analysis. The effect of the SnCl4 precursor flow on the morphology of the GeSn shell grown around 100 nm Ge cores is shown in Fig. 1. A fixed growth time of 2 h was used in combination with a Ge/Sn ratio in gas phase ranging from 1285 to 300. An increase in the diameter of the core/shell NWs is visible with increasing (decreasing) supply of SnCl4

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“…Germanium-tin shells were grown on germanium nanowires grown by gold catalyzed vapor-liquid-solid (VLS) growth similar to previous work. 11,16 Ge core nanowires were grown at a total pressure of 30 Torr. The process consisted of a 6 minutes anneal at 375°C under hydrogen followed by a 4 minutes nucleation step 375°C under 0.47 Torr GeH 4 , which was used to initiate Ge nanowires.…”

Section: Methodsmentioning

confidence: 99%

“…10 Specifically for the Ge-Sn system, the formation of core-shell Ge/Ge 1−x Sn x NWs (by chemical vapor deposition) provides a plausible solution to obtain defect-free Ge 1−x Sn x , where a high Sn concentration can be achieved, well beyond its bulk solubility in Ge. [11][12][13] In addition, due to the lattice mismatch between Ge and Ge 1−x Sn x , a direct band gap condition of the Ge core may be achieved by tensile straining. 14 To achieve better control over the quality and yield of the core-shell nanowires, a better understanding of the wire growth mechanisms is of great significance.…”

Section: Introductionmentioning

confidence: 99%

Phase-field investigation of the stages in radial growth of core–shell Ge/Ge_1−xSn_x nanowires

et al. 2019

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Core-Shell Germanium/Germanium–Tin Nanowires Exhibiting Room-Temperature Direct- and Indirect-Gap Photoluminescence

Cited by 65 publications

References 38 publications

Growth of Ge_1−xSn_x Nanowires by Chemical Vapor Deposition via Vapor–Liquid–Solid Mechanism Using GeH₄ and SnCl₄

Growth of Ge_1−xSn_x Nanowires by Chemical Vapor Deposition via Vapor–Liquid–Solid Mechanism Using GeH₄ and SnCl₄

Kinetic Control of Morphology and Composition in Ge/GeSn Core/Shell Nanowires

Phase-field investigation of the stages in radial growth of core–shell Ge/Ge_1−xSn_x nanowires

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Core-Shell Germanium/Germanium–Tin Nanowires Exhibiting Room-Temperature Direct- and Indirect-Gap Photoluminescence

Cited by 65 publications

References 38 publications

Growth of Ge1−xSnx Nanowires by Chemical Vapor Deposition via Vapor–Liquid–Solid Mechanism Using GeH4 and SnCl4

Growth of Ge1−xSnx Nanowires by Chemical Vapor Deposition via Vapor–Liquid–Solid Mechanism Using GeH4 and SnCl4

Kinetic Control of Morphology and Composition in Ge/GeSn Core/Shell Nanowires

Phase-field investigation of the stages in radial growth of core–shell Ge/Ge1−xSnx nanowires

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Growth of Ge_1−xSn_x Nanowires by Chemical Vapor Deposition via Vapor–Liquid–Solid Mechanism Using GeH₄ and SnCl₄

Growth of Ge_1−xSn_x Nanowires by Chemical Vapor Deposition via Vapor–Liquid–Solid Mechanism Using GeH₄ and SnCl₄

Phase-field investigation of the stages in radial growth of core–shell Ge/Ge_1−xSn_x nanowires