Computational prediction of two-dimensional group-IV mono-chalcogenides

Density functional calculations determine the structure, stability, and electronic properties of two-dimensional materials in the family of group-IV monochalcogenides, MX (M = Ge, Sn, Pb; X = O, S, Se, Te). Calculations with a van der Waals functional show that the two-dimensional IV-VI compounds ar...

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Bibliographic Details
Published in:Applied physics letters 2014-07, Vol.105 (4)
Main Authors: Singh, Arunima K., Hennig, Richard G.
Format: Article
Language:English
Subjects:
Applied physics
CHALCOGENIDES
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
CONFINEMENT
CRYSTAL STRUCTURE
DENSITY FUNCTIONAL METHOD
Dimensional stability
Dynamic stability
ELECTRICAL PROPERTIES
FORECASTING
FORMATION HEAT
Free energy
Germanium
Heat of formation
Heterostructures
Lead
Mathematical analysis
Molybdenum disulfide
MOLYBDENUM SULFIDES
Optoelectronics
PHONONS
Quantum confinement
Selenium
SEMICONDUCTOR MATERIALS
Sodium chloride
SODIUM CHLORIDES
SOLAR CELLS
SOLAR ENERGY CONVERSION
SPECTRA
STABILITY
Structural stability
Tin
TWO-DIMENSIONAL CALCULATIONS
VAN DER WAALS FORCES
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Summary:Density functional calculations determine the structure, stability, and electronic properties of two-dimensional materials in the family of group-IV monochalcogenides, MX (M = Ge, Sn, Pb; X = O, S, Se, Te). Calculations with a van der Waals functional show that the two-dimensional IV-VI compounds are most stable in either a highly distorted NaCl-type structure or a single-layer litharge type tetragonal structure. Their formation energies are comparable to single-layer MoS2, indicating the ease of mechanical exfoliation from their layered bulk structures. The phonon spectra confirm their dynamical stability. Using the hybrid HSE06 functional, we find that these materials are semiconductors with bandgaps that are generally larger than for their bulk counterparts due to quantum confinement. The band edge alignments of monolayer group IV-VI materials reveal several type-I and type-II heterostructures, suited for optoelectronics and solar energy conversion.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4891230