Drastic Changes in Material Composition and Electrical Properties of Gallium-Seeded Germanium Nanowires

Seifner, Michael S.; Sistani, Masiar; Živadinović, Ivan; Bartmann, Maximilian G.; Lugstein, Alois; Barth, Sven

doi:10.1021/acs.cgd.9b00210

Cited by 6 publications

(7 citation statements)

References 46 publications

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“…Liquid metals are natural media for growing inorganic crystals. − For crystalline inorganic semiconductors, elemental liquid metals in vapor–liquid–solid (VLS) and liquid-phase epitaxy (LPE) processes have been explored and utilized successfully. − In this regard, the choice of the liquid metal is known to strongly influence how the inorganic solute becomes a crystalline material. So far, the overwhelming majority of studies have focused largely on just unary liquid metals and the corresponding binary solvent/solute mixtures.…”

Section: Introductionmentioning

confidence: 99%

Evidence for Facilitated Surface Transport during Ge Crystal Growth by Indium in Liquid Hg–In Alloys at Room Temperature

Pattadar

Cheek

Sartori

et al. 2021

Crystal Growth & Design

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Room-temperature electrodeposition of Ge crystallites was investigated by the electrochemical liquid–liquid–solid (ec-LLS) process using a family of Hg1–x In x alloys. The objective was to determine whether different liquid metal alloys with nominally the same bulk solubility toward Ge but potentially different surface character would yield any differences in the resultant Ge crystallites. Variation of the In fraction in these alloys was the control variable. The following details were ascertained from the cumulative data. First, in accordance with thermodynamic predictions, the surface of Hg x In1–x alloys was strongly enriched with Hg according to X-ray specular reflectivity data. These data further indicated that the surface enrichment was confined exclusively to a single atomic layer at the liquid metal surface. These properties of the Hg1–x In x /electrolyte interface structure facilitated the first two steps of the ec-LLS process. Second, the presence of In influenced the morphology of the resultant Ge crystallites from ec-LLS, in accordance with mediated transport of the Ge upon initial electroreduction. Specifically, X-ray diffraction, Raman, and microscopy data suggest that a strong affinity between In and Ge that affects the crystal morphology. This study thus motivates further exploration of both In as a component in liquid metal solvents to facilitate grain size and more general studies detailing how the surface structure and composition of liquid metals influence crystal growth. These findings significantly advance the prospect for preparing technologically relevant inorganic crystalline semiconductors at low temperatures.

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Section: Introductionmentioning

confidence: 99%

Evidence for Facilitated Surface Transport during Ge Crystal Growth by Indium in Liquid Hg–In Alloys at Room Temperature

Pattadar

Cheek

Sartori

et al. 2021

Crystal Growth & Design

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“…[3] Modifications of the catalyst have been shown to yield intermediate morphologies with tilted vdWs layering. [19] While posing significant synthesis challenges, ultrathin 3D-crystalline semiconductor nanowires have been realized for a variety of materials, including Si, [20,21] Ge, [22][23][24] ZnS, [25] CsPbBr 3 , [26] Bi 2 S 3 , [27] GaSb, [28] ZnSe, [29] InAs, [30] Ga 2 O 3 , [31] Mo 6 Te 6 , [32] etc., where they displayed size-dependent properties substantially different from their thicker counterparts such as different crystal orientations, [20,28] absence of defects such as stacking faults or twins, [30] strong quantum confinement, [21,26,33,34] large anisotropic lattice expansion, [25] intrinsic room temperature ferromagnetism, [25] unusually high thermal conductivity, [35] etc. In addition, dislocated, Eshelbytwisted 3D-crystalline nanowires (PbSe, PbS, [36] InP [37] ) show an enhanced twist rate at ultrathin diameters compared to Eshelby's continuum model, [14] attributed to surface relaxation effects.…”

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confidence: 99%

Ultrathin Twisted Germanium Sulfide van der Waals Nanowires by Bismuth Catalyzed Vapor–Liquid–Solid Growth

Sutter

2021

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ability to carry traveling waveguide modes at visible and near-infrared energies. [12] Van der Waals (vdWs) nanowires carrying axial screw dislocations are of particular interest for 3D twistronics. [13] Eshelby twist due to the screw dislocation [14] endows such wires with an inherent chiral structure in which the progressive rotation of the crystal axes translates (at the unit cell level) into interlayer twist that is stabilized by the dislocation and precisely (to ≈1/100°) [15] tunable via the nanowire diameter. The underlying twist moiré, realized here on a helicoid surface rather than a planar vdWs interface (IF) as in the conventional twisted homo-and heterostructures, [16] can modulate the bandgap and the local optoelectronic properties. [17] vdWs nanowires have been synthesized with high crystal quality using vapor-liquid-solid (VLS) growth, in which a liquid catalyst drop at the tip of the growing wire transports material from the vapor phase to the nanowire growth front. As in the growth of conventional 3D-crystalline (e.g., Si, Ge) nanowires, [18] the catalyst thus defines the positioning on the substrate and the diameter of the growing nanowire. In addition, in the growth of layered nanowires, the VLS catalyst defines the stacking of layers, which can be longitudinal, that is, with layer stacking along the wire axis, [15] or transverse, that is, ribbon-like with layers aligned along the wire axis. [3] Modifications of the catalyst have been shown to yield intermediate morphologies with tilted vdWs layering. [19] While posing significant synthesis challenges, ultrathin 3D-crystalline semiconductor nanowires have been realized for a variety of materials, including Si, [20,21] Ge, [22][23][24] ZnS, [25] CsPbBr 3 , [26] Bi 2 S 3 , [27] GaSb, [28] ZnSe, [29] InAs, [30] Ga 2 O 3 , [31] Mo 6 Te 6 , [32] etc., where they displayed size-dependent properties substantially different from their thicker counterparts such as different crystal orientations, [20,28] absence of defects such as stacking faults or twins, [30] strong quantum confinement, [21,26,33,34] large anisotropic lattice expansion, [25] intrinsic room temperature ferromagnetism, [25] unusually high thermal conductivity, [35] etc. In addition, dislocated, Eshelbytwisted 3D-crystalline nanowires (PbSe, PbS, [36] InP [37] ) show an enhanced twist rate at ultrathin diameters compared to Eshelby's continuum model, [14] attributed to surface relaxation effects. [37] In contrast to 3D-crystalline materials, ultrathin vdWs nanowires have remained elusive so far. Reaching the ultrathin regime is critical for addressing fundamental questions 1D nanowires of 2D layered crystals are emerging nanostructures synthesized by combining van der Waals (vdW) epitaxy and vapor-liquid-solid (VLS) growth. Nanowires of the group IV monochalcogenide germanium sulfide (GeS) are of particular interest for twistronics due to axial screw dislocations giving rise to Eshelby twist and precision interlayer twist at helical vdW interfaces. Ultrathin vdW nanowires have not been rea...

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“…Two growth regimes in the Ga-seeded Ge NW growth have been determined, changing the growth temperature. 528 The high efficiency of Ga incorporation has been observed at temperatures below 350 °C with Ga contents in the ∼3.8 atom % range, while higher growth temperatures of 390 °C lead to Ge NWs without Ga incorporation according to STEM-EDX analyses. Small Ga concentrations below the detection limit of STEM-EDX would result in p-type behavior of the produced NWs, which has not been observed in the electronic measurements using single NW devices.…”

Section: Metastable Group IV Nanostructuresmentioning

confidence: 95%

“…In addition, the Ga-hyperdoped Ge NWs reveal metal-like behavior in temperature dependent resistivity evolution. Two growth regimes in the Ga-seeded Ge NW growth have been determined, changing the growth temperature . The high efficiency of Ga incorporation has been observed at temperatures below 350 °C with Ga contents in the ∼3.8 atom % range, while higher growth temperatures of 390 °C lead to Ge NWs without Ga incorporation according to STEM-EDX analyses.…”

Section: Metastable Group IV Nanostructuresmentioning

confidence: 98%

Metastable Group IV Allotropes and Solid Solutions: Nanoparticles and Nanowires

2020

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In the past decades, group IV nanowires and nanoparticles have been the subject of extensive research. Beside tremendous progress in morphological control and integration in advanced device architectures, research on allotropes and metastable compositions has gained considerable interest. Several new approaches now allow the controlled formation of specific allotropes in the nanostructured form as well as chemical compositions not attainable by traditional synthesis protocols. The conditions applied to form these metastable solid solutions and allotropes are usually far from thermodynamic equilibrium or rely on unconventional templates. The increased interest in the field of metastable group IV nanostructures arises from their altered physical properties, including tunable, direct bandgaps with energies equivalent to the near- to mid-infrared spectral region as described for materials such as Ge1–x Sn x and hexagonal Si1–x Ge x . The implementation of these material characteristics in complementary metal oxide semiconductor (CMOS) processes are desirable for applications in electronics, optoelectronics, sensors, optics, etc. but also their use as nonsurface bound nanoparticles in sensing, nanobiotechnology and nanomedicine can offer additional opportunities. This review article highlights both the important advancements and still open questions for the continued development of these nanoscaled materials for next-generation device concepts.

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Drastic Changes in Material Composition and Electrical Properties of Gallium-Seeded Germanium Nanowires

Cited by 6 publications

References 46 publications

Evidence for Facilitated Surface Transport during Ge Crystal Growth by Indium in Liquid Hg–In Alloys at Room Temperature

Evidence for Facilitated Surface Transport during Ge Crystal Growth by Indium in Liquid Hg–In Alloys at Room Temperature

Ultrathin Twisted Germanium Sulfide van der Waals Nanowires by Bismuth Catalyzed Vapor–Liquid–Solid Growth

Metastable Group IV Allotropes and Solid Solutions: Nanoparticles and Nanowires

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