Synthesis, structure, and electronic properties of 4H-germanium

Kiefer, Florian; Hlukhyy, Viktor; Karttunen, Antti J.; Fässler, Thomas F.; Gold, Christian; Scheidt, Ernst‐Wilhelm; Scherer, Wolfgang; Nylén, Johanna; Häußermann, Ulrich

doi:10.1039/b921575a

Cited by 36 publications

(63 citation statements)

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“…60 However a recent finding through B3LYP calculations suggests a direct band gap of 0.81 eV located at Γ point for 4H-Ge while the same calculation yields a band gap of α-Ge as 0.83 eV. 61 In both scenarios, hexagonal 4H-Ge region can form a region up to few nanometers with altered band structure in a 3C-Ge nanowire host lattice.…”

Section: Polytype and Twin Formation In Nanowiresmentioning

confidence: 99%

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Diameter-Controlled Germanium Nanowires with Lamellar Twinning and Polytypes

et al. 2015

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Type of publicationArticle (peer-reviewed) Link to publisher's versionhttp://pubs.acs.org/journal/cmatex http://dx.doi.org/10.1021/acs.chemmater.5b00697Access to the full text of the published version may require a subscription. are appealing for use in nanowire devices. This paper details the influence of colloidal magnetite iron oxide nanoparticle seeds to regulate the radial dimension and twin boundary formation in Ge nanowires grown through a liquid-injection chemical vapor deposition process. Control over the mean nanowire diameter, even in the sub-10 nm regime, was achieved due to the minimal expansion and aggregation of iron oxide nanoparticles during the growth process. The uncommon occurrence of heterogeneously distributed multiple layer {111} twins, directed perpendicular to the nanowire growth axis, were also observed in <111>-directed Ge nanowires, especially those synthesized from patterned hemispherical Fe3O4 nanodot catalysts. Consecutive twin planes along <111>-oriented nanowires resulted in a local phase transformation from 3C diamond cubic to hexagonal 4H allotrope. Localized polytypic crystal phase heretostructures were formed along <111>-oriented Ge nanowire using magnetite nanodot catalysts. Rights

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Section: Polytype and Twin Formation In Nanowiresmentioning

confidence: 99%

“…64 The observed peak at 284 cm -1 is due to the presence of 4H Ge, as confirmed from TEM analysis of corresponding Ge nanowires ( Figure 6(b)) and is consistent with the earlier reports. 61 We …”

Section: Polytype and Twin Formation In Nanowiresmentioning

confidence: 99%

Diameter-Controlled Germanium Nanowires with Lamellar Twinning and Polytypes

et al. 2015

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“…The R8 ( R ) phase has also been observed during decompression141520 and hydrostaticity has been suggested as an important parameter for phases selection22. At ambient pressure, chemical methods have been used to produce Ge in the form of clathrates23, 4H and so-called allo-Ge242526. As members of elemental group IV, similar structures are often observed for both Ge and Si, for example, DC, BC8/R8 and ST12.…”

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Properties of the exotic metastable ST12 germanium allotrope

et al. 2017

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The optical and electronic properties of semiconducting materials are of great importance to a vast range of contemporary technologies. Diamond-cubic germanium is a well-known semiconductor, although other ‘exotic' forms may possess distinct properties. In particular, there is currently no consensus for the band gap and electronic structure of ST12-Ge (tP12, P43212) due to experimental limitations in sample preparation and varying theoretical predictions. Here we report clear experimental and theoretical evidence for the intrinsic properties of ST12-Ge, including the first optical measurements on bulk samples. Phase-pure bulk samples of ST12-Ge were synthesized, and the structure and purity were verified using powder X-ray diffraction, transmission electron microscopy, Raman and wavelength/energy dispersive X-ray spectroscopy. Optical measurements indicate that ST12-Ge is a semiconductor with an indirect band gap of 0.59 eV and a direct optical transition at 0.74 eV, which is in good agreement with electrical transport measurements and our first-principles calculations.

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“…A series of Ge allotropes composed of Ge 9 units have been theoretically proposed 18. Nanosized germanium particles are obtained when the Zintl phase A 4 Ge 4 (A=Na, K) reacts with GeCl 4 in a metathesis reaction,19–22 and Ge allotropes can be obtained by delithiation of lithium germanides 23. An alternative way for varying the semiconducting properties could be the implementation of transition metals in homoatomic polyanionic clusters, as achieved in [Co@Ge 10 ] 3− , [(Ni‐Ni‐Ni)@(Ge 9 ) 2 ] 4− , and [Au 3 Ge 45 ] 9−[24–26] among several examples.…”

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confidence: 99%