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HL: Fachverband Halbleiterphysik
HL 56: 2D Materials and their Heterostructures II (joint session DS/HL/O)
HL 56.4: Vortrag
Donnerstag, 19. März 2020, 10:15–10:30, CHE 89
Semiconducting defect-free polymorph of borophene: Peierls distortion in two dimensions — Semran Ipek2, Aybey Mogulkoc1, •Seymur Cahangirov2, and Engin Durgun2 — 1Department of Physics, Ankara University, 06100, Ankara, Turkey — 2UNAM and Institute of Materials Science and Nanotechnology, Bilkent University, 06800, Ankara, Turkey
In contrast to the well-defined lattices of various two-dimensional (2D) systems, the atomic structure of borophene is sensitive to growth conditions and type of the substrate which results in rich polymorphism. By employing ab initio methods, we reveal a thermodynamically stable borophene polymorph without vacancies which is a semiconductor unlike the other known boron sheets, in the form of an asymmetric centered-washboard structure. Our results indicate that asymmetric distortion is induced due to Peierls instability which transforms a symmetric metallic system into a semiconductor. We also show that applying uniaxial or biaxial strain gradually lowers the obtained band gap and the symmetric configuration is restored following the closure of the band gap. Furthermore, while the Poisson's ratio is calculated to be high and positive in the semiconducting regime, it switches to negative once the metallicity is retrieved. The realization of semiconducting borophene polymorphs without defects and tunability of its electronic and mechanical response can extend the usage of boron sheets in a variety of nanoelectronic applications