Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 35: 2D Materials I: Growth and Properties of Transition Metal Dichalcogenides, Phase Transitions

O 35.8: Vortrag

Dienstag, 2. April 2019, 15:45–16:00, H14

Reversible crystalline-to-amorphous phase transition in MoS₂ on Gr/Ir(111) by ion irradiation — •Philipp Valerius¹, Joshua Hall¹, Silvan Kretschmer², Mahdi Ghorbani-Asl², Alexander Grüneis¹, Arkady V. Krasheninnikov^2,3, and Thomas Michely¹ — ¹Universität zu Köln, Germany — ²Helmholtz-Zentrum Dresden-Rossendorf, Germany — ³Aalto University, Finland

Grazing incidence 500 eV Xe⁺ irradiation transforms a crystalline monolayer of MoS₂ resting on Gr/Ir(111) into an amorphous material as shown by LEED and STM measurements. Moreover, a significant density of states in the band gap evolve, which is evidenced by scanning tunneling spectroscopy. Molecular dynamics simulations uncover that under the irradiation conditions used, sulfur is selectively removed from the top layer, while Mo and the bottom S layer is not sputtered. Through annealing in S vapor, the MoS₂ can be restored as a crystalline semiconductor close to perfection. The structural phase transitions are accompanied by changes in the Raman modes and photoluminescence. As the amorphized MoS₂ monolayer displays metallic properties, selective ion beam amorphization of contact areas could be used as a method to avoid Schottky barriers when contacting MoS₂.