Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 39: 2D Materials III: Growth and Heterostructures (joint session O/HL)
O 39.4: Talk
Tuesday, March 17, 2020, 11:15–11:30, GER 38
Where the MoS2 bilayer grows: An in situ LEEM study — •Moritz Ewert1,2, Lars Buß1,2, Francesca Genuzio3, Tevfik Onur Menteş3, Andrea Locatelli3, Jens Falta2, and Jan Ingo Flege1,2 — 1Applied Physics and Semiconductor Spectroscopy, Brandenburg University of Technology Cottbus-Senftenberg, Germany — 2Institute of Solid State Physics, University of Bremen, Germany — 3Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Trieste 34012, Italy
Molybdenum disulfide (MoS2) is well-known for changing from an indirect to a direct semiconductor when its thickness is reduced to a single layer, rendering a high degree of growth control a necessity for optoelectronic applications. An extensively investigated model system is MoS2 on Au(111), which using molecular beam epitaxy typically grows as clusters. Here, we present an in-situ low-energy electron microscopy (LEEM) study of the extended growth of MoS2 at 700∘C and 750∘C. These conditions lead to the formation of micron-sized single-layer MoS2 islands. The single-domain character of these islands is demonstrated by employing dark-field imaging and micro-diffraction (LEED), which allow quantifying the relative coverage of the two mirror domains. Furthermore, selected area angle-resolved photoelectron spectroscopy of these domains directly confirms their threefold symmetric electronic bandstructure. Interestingly, under certain conditions subsequent structural characterization by I(V)-LEEM clearly identifies regions where a bilayer of MoS2 has nucleated. Parameters influencing the bilayer growth as well as its electronic properties will be discussed.