Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 36: 2D materials beyond graphene: TMDCs, silicene and relatives I
O 36.3: Vortrag
Dienstag, 13. März 2018, 14:30–14:45, MA 043
Characterisation of Defects in black phosphorus and phosphorene — •Julian Gaberle1, Alexander Shluger1, Mark Wentik1, Tony Kenyon1, and Alexander Schwarz2 — 1University College London, WC1E 6BT London, UK — 2University of Hamburg, 20355 Hamburg, Germany
Interest in black phosphorus as a post graphene material has attracted considerable attention since 2014. Similar to graphene it consists of vdW bonded layers of covalently bonded phosphorus atoms. However, unlike graphene BP has a tunable direct bandgap, displays very high hole mobility and current switching ratios, which make it an interesting candidate for modern technologies.However, in order to make the transition from research labs to modern technologies the fundamental properties of BP and phosphorene need to be better understood. In particular point defects in the lattice and their effect on the electronic properties of BP are still not fully understood.
To characterise these defects, STM imaging was performed on black phosphorus and extended anisotropic defect states were observed. These defects have previously been attributed to phosphorus vacancies, but recently it has been suggested that Sn impurities are an alternative defect source. In oder to better understand the nature of the defect, atomically resolved AFM imaging and XPS was performed. Combining state of the art experiments with ab initio DFT modelling of vacancies and impurities, we were able to eliminate Sn impurities as a likely source of these defects and propose that these are indeed vacancies created in the cleavage process.