Berlin 2024 – scientific programme
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O: Fachverband Oberflächenphysik
O 79: 2D Materials V: Growth, Structure and Substrate Interaction
O 79.6: Talk
Thursday, March 21, 2024, 11:45–12:00, MA 005
Isolating the optical response of a MoS2 monolayer under extreme screening of a metal — •Tao Yang1, Stephan Sleziona1, Erik Pollmann1, Eckart Hasselbrink2, Peter Kratzer1, Marika Schleberger1, R. Kramer Campen1, and Yujin Tong1 — 1Fakultät für Physik, Universität of Duisburg-Essen, Germany — 2Fakultät für Chemie, Universität of Duisburg-Essen, Germany
Transition metal dichalcogenides monolayers, as two-dimensional (2D) direct bandgap semiconductors, hold promise for advanced optoelectronic and photocatalytic devices. Interaction with three-dimensional (3D) metals, like Au, profoundly affects their optical properties, posing challenges in characterizing the monolayer’s optical responses within the semiconductor-metal junction. In this study, using precise polarization-controlled final-state sum frequency generation (FS-SFG), we successfully isolated the optical responses of a MoS2 monolayer from a MoS2/Au junction. The resulting SFG spectra exhibit a linear lineshape without A or B exciton features, attributed to strong dielectric screening and substrate induced doping. The linear lineshape illustrates the expected constant density of states at the band edge of the 2D semiconductor, typically obscured by excitonic interactions in weak-screening conditions. Extrapolation yields the onset of a direct quasiparticle bandgap of about 1.65±0.20 eV, indicating significant bandgap renormalization. This study enriches understanding of the optical responses of a 2D semiconductor in extreme screening conditions and provides a critical reference for 2D semiconductor-based photocatalytic applications.
Keywords: transition metal dichalcogenides; 2D materials; bandgap renormalization; nonlinear optics