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Genetic algorithm prediction of two-dimensional group-IV dioxides for dielectrics

Arunima K. Singh, Benjamin C. Revard, Rohit Ramanathan, Michael Ashton, Francesca Tavazza, and Richard G. Hennig
Phys. Rev. B 95, 155426 – Published 18 April 2017
Physics logo See Synopsis: A Crystal Ball for 2D Materials
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Abstract

Two-dimensional (2D) materials present a new class of materials whose structures and properties can differ from their bulk counterparts. We perform a genetic algorithm structure search using density-functional theory to identify low-energy structures of 2D group-IV dioxides AO2 (A=Si, Ge, Sn, Pb). We find that 2D SiO2 is most stable in the experimentally determined bi-tetrahedral structure, while 2D SnO2 and PbO2 are most stable in the 1T structure. For 2D GeO2, the genetic algorithm finds a new low-energy 2D structure with monoclinic symmetry. Each system exhibits 2D structures with formation energies ranging from 26 to 151 meV/atom, below those of certain already synthesized 2D materials. The phonon spectra confirm their dynamic stability. Using the HSE06 hybrid functional, we determine that the 2D dioxides are insulators or semiconductors, with a direct band gap of 7.2 eV at Γ for 2D SiO2, and indirect band gaps of 4.8–2.7 eV for the other dioxides. To guide future applications of these 2D materials in nanoelectronic devices, we determine their band-edge alignment with graphene, phosphorene, and single-layer BN and MoS2. An assessment of the dielectric properties and electrochemical stability of the 2D group-IV dioxides shows that 2D GeO2 and SnO2 are particularly promising candidates for gate oxides and 2D SnO2 also as a protective layer in heterostructure nanoelectronic devices.

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  • Received 7 November 2016

DOI:https://doi.org/10.1103/PhysRevB.95.155426

©2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Synopsis

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A Crystal Ball for 2D Materials

Published 18 April 2017

Researchers predict new two-dimensional materials whose structures differ from their three-dimensional counterparts.

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Authors & Affiliations

Arunima K. Singh1,2, Benjamin C. Revard3,4, Rohit Ramanathan3, Michael Ashton4, Francesca Tavazza1, and Richard G. Hennig3,4,*

  • 1Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
  • 2Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
  • 3Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14850, USA
  • 4Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611, USA

  • *rhennig@ufl.edu

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Issue

Vol. 95, Iss. 15 — 15 April 2017

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