Berlin 2024 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 54: Scanning Probe Microscopy: Light Matter Interaction at Atomic Scales I

O 54.9: Vortrag

Mittwoch, 20. März 2024, 17:30–17:45, MA 041

Amplitude Calibration for THz-STM of Atomic Defects in 2D Semiconductors — •Laric Bobzien, Jonas Allerbeck, Spencer Eve Ammermann, and Bruno Schuler — nanotech@surfaces, Empa -Swiss Federal Laboratories for Material Science and Technology, Überlandstrasse 129, 8600 Dübendorf Switzerland

The fundamental understanding of quantum dynamics in low-dimensional materials requires simultaneous ultrafast temporal and atomic spatial resolution, achievable with ultrafast STM. Here, single-cycle THz-pulse-driven STM (THz-STM) combines the atomic spatial resolution with picosecond temporal resolution of the THz field. Point defects in 2D semiconductors, such as vacancies or impurities, are a perfect model systems to investigate strongly correlated dynamics in low dimensions and offer a rich playground for understanding dynamics in the atomic regime. We study point defects in a prototypical family of 2D semiconductors, transition metal dichalcogenides (TMDs), with our multi-MHz repetition rates and efficient THz-STM.

I will show recent measurements of the THz rectified charge as a function of bias and THz field amplitude on 2D TMDs. This allows to map the complex energy landscape of localized states with a resolution of down to 0.01 electrons per pulse enabling precise near-field amplitude calibration. Preliminary THz-STM and THz-STS measurements of a sulfur vacancy in monolayer MoS2 demonstrate state-selective tunneling into distinct electronic orbitals of the quantum defect. These findings pave the way for exploring atomic systems at their native length and time scale.

Keywords: Ultrafast scanning probe microscopy; THz-STM; atomic defects; 2D semiconductors; field-driven tunneling