Fully and partially iodinated germanane as a platform for the observation of the quantum spin Hall effect

Padilha, J. E.; Abdalla, Leonardo; Silva, A. J. R. da; Fazzio, A.

doi:10.1103/physrevb.93.045135

Cited by 19 publications

(11 citation statements)

References 41 publications

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“…For example, a 2D topological phase having room temperature quantum spin Hall (QSH) behavior is predicted to occur in tin graphane analogues, when the tin lattice is terminated with halogen or hydroxyl ligands, but not hydrogen . QSH behavior has also been predicted in iodine-terminated germanane or methyl-terminated germanane (GeCH 3 ) having 12% tensile strain. , As another example, hydrogen-terminated silicane is predicted to have an indirect gap at 2.9 eV, while termination with different ligands converts it into a material with a direct gap ranging from 2.1 to 2.5 eV . As the covalent functionalization of numerous families of 2D materials, including the group 14 graphane analogues, − transition metal dichalcogenides, − phosphorene, and MXenes, − is starting to be established, systematically understanding how and to what extent the electronic structure can be tailored by the identity of the ligand is essential to effectively utilize functionalization chemistry to rationally tailor properties.…”

Section: Introductionmentioning

confidence: 99%

Tailoring the Electronic Structure of Covalently Functionalized Germanane via the Interplay of Ligand Strain and Electronegativity

et al. 2016

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The covalent functionalization of 2D crystals is an emerging route for tailoring the electronic structure and generating novel phenomena. Understanding the influence of ligand chemistry will enable the rational tailoring of their properties. Through the synthesis of numerous ligand-functionalized germanane crystals, we establish the role of ligand size and electronegativity on functionalization density, framework structure, and electronic structure. Nearly uniform termination only occurs with small ligands. Ligands that are too sterically bulky will lead to partial hydrogen termination of the framework. With a homogeneous distribution of different ligands, the band gaps and Raman shifts are dictated by their relative stoichiometry in a pseudolinear fashion similar to Vegard's law. Larger and more electronegative ligands expand the germanane framework, thereby lowering the band gap and Raman shift. Simply by changing the identity of the organic ligand, the band gap can be tuned by ∼15%, highlighting the power of functionalization chemistry to manipulate the properties of single-atom thick materials.

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Section: Introductionmentioning

confidence: 99%

Tailoring the Electronic Structure of Covalently Functionalized Germanane via the Interplay of Ligand Strain and Electronegativity

et al. 2016

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“…7 Furthermore, some proposals advocate that topological states emerge in the covalently functionalized Xane derivatives. For instance, a 2D topological insulator is expected in halogen-functionalized germanane GeX (X = H, F, Cl, Br), methyl-substituted GeCH 3 [16][17][18] and ethynyl-derivative of germanene GeC 2 X (X = H, halogen) 19 under sizeable tensile strain.…”

Section: Introductionmentioning

confidence: 99%

Designing 3D topological insulators by 2D-Xene (X = Ge, Sn) sheet functionalization in GaGeTe-type structures

et al. 2017

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State-of-the-art theoretical studies anticipate a 2D Dirac system in the ''heavy'' analogues of graphene, free-standing buckled honeycomb-like Xenes (X = Si, Ge, Sn, Pb, etc.). Herewith we regard a 2D sheet, which structurally and electronically resembles Xenes, in a 3D periodic, rhombohedral structure of layered AXTe (A = Ga, In; X = Ge, Sn) bulk materials. This structural family is predicted to host a 3D strong topological insulator with Z 2 = 1;(111) as a result of functionalization of the Xene derivative by covalent interactions. The parent structure GaGeTe is a long-known bulk semiconductor; the ''heavy'', isostructural analogues InSnTe and GaSnTe are predicted to be dynamically stable. Spin-orbit interaction in InSnTe opens a small topological band gap with inverted gap edges that are mainly composed of the In-5s and Te-5p states. Our simulations classify GaSnTe as a semimetal with topological properties, whereas the verdict for GaGeTe is not conclusive and urges further experimental verification. The AXTe family structures can be regarded as stacks of 2D layered cut-outs from a zincblende-type lattice and are composed of elements that are broadly used in modern semiconductor devices; hence they represent an accessible, attractive alternative for applications in spintronics. The layered nature of AXTe should facilitate the exfoliation of their hextuple layers and manufacture of heterostructures.

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“…Free-standing germanene layer was theoretically predicted in 2009, reporting a narrow band gap opening (about 0.024 eV) compared to the zero band gap of graphene. This promotes a quantum-spin Hall effect and massless Dirac Fermions, that together with the tunable band gap, , makes germanene’s use realistic for optoelectronics, − sensing, − energy storage, − and catalysis. ,, The electronic and magnetic properties of buckled germanene are size and geometry determined and can be tuned by strain , or surface functionalization. − It is worth noting that germanene stability is low, however, germanene derivates are stable. For example, germanane (“hydrogenated germanene”, Ge–H) or methyl germanane (“methyl terminated germanene”, Ge–CH 3 ) are the most stable and studied forms. , Nevertheless, it has not yet been electrochemically exfoliated from bulk germanium …”

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Edge-Hydrogenated Germanene by Electrochemical Decalcification-Exfoliation of CaGe₂: Germanene-Enabled Vapor Sensor

2021

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Two-dimensional germanene has been recently explored for applications in sensing, catalysis, and energy storage. The potential of this van der Waals material lies in its optoelectronic and chemical properties. However, pure free-standing germanene cannot be found in nature, and the synthesis methods are hindering the potentially fascinating properties of germanene. Herein, we report a single-step synthesis of few-layer germanene by electrochemical exfoliation in a nonaqueous environment. As a result of simultaneous decalcification and intercalation of the electrolyte’s active ions, we achieved low-level hydrogenation of germanene that occurs at the edges of the material. The obtained edge-hydrogenated germanene flakes have a lateral size of several micrometers and possess a cubic structure. We have pioneered the potential application of edge-hydrogenated germanene for vapor sensing and demonstrated its specific sensitivity to methanol and ethanol. Furthermore, we have shown a selective behavior of the germanene-based sensor that appears to increase the electrical resistance in the vapors where methanol prevails. We anticipate that these results can provide an approach for emerging layered materials with the potential utility in advanced gas sensing.

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Fully and partially iodinated germanane as a platform for the observation of the quantum spin Hall effect

Cited by 19 publications

References 41 publications

Tailoring the Electronic Structure of Covalently Functionalized Germanane via the Interplay of Ligand Strain and Electronegativity

Tailoring the Electronic Structure of Covalently Functionalized Germanane via the Interplay of Ligand Strain and Electronegativity

Designing 3D topological insulators by 2D-Xene (X = Ge, Sn) sheet functionalization in GaGeTe-type structures

Edge-Hydrogenated Germanene by Electrochemical Decalcification-Exfoliation of CaGe₂: Germanene-Enabled Vapor Sensor

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Fully and partially iodinated germanane as a platform for the observation of the quantum spin Hall effect

Cited by 19 publications

References 41 publications

Tailoring the Electronic Structure of Covalently Functionalized Germanane via the Interplay of Ligand Strain and Electronegativity

Tailoring the Electronic Structure of Covalently Functionalized Germanane via the Interplay of Ligand Strain and Electronegativity

Designing 3D topological insulators by 2D-Xene (X = Ge, Sn) sheet functionalization in GaGeTe-type structures

Edge-Hydrogenated Germanene by Electrochemical Decalcification-Exfoliation of CaGe2: Germanene-Enabled Vapor Sensor

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Edge-Hydrogenated Germanene by Electrochemical Decalcification-Exfoliation of CaGe₂: Germanene-Enabled Vapor Sensor