Dresden 2026 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 3: 2D Materials I – Excitonic properties
HL 3.5: Vortrag
Montag, 9. März 2026, 10:30–10:45, POT/0081
Substrate interaction on local exciton/trion ratio in mono- to few-layer WS2 — •Appanna Parvangada1,2, Dmitrii Sychev1, and Ilka Hermes1 — 1Leibniz Institute of Polymer Research Dresden e.V., Dresden, Germany — 2Institute of Applied Physics, Dresden University of Technology, Dresden, Germany
Two-dimensional Tungsten Disulfide (WS2) possesses distinctive optoelectronic properties such as high photoluminescence yield, a tunable band gap, large exciton binding, quantum confinement, strong-light matter interaction. The combination with low dimensionality makes them a favorable candidate for a variety of lightweight and flexible optoelectronic devices such as photodetectors, solar cells and LEDs.
However, large-scale industrial implementation of optoelectronic 2D materials is often impeded by their high spatial heterogeneity, caused by nanoscale variations in layer thickness, substrates interactions and local strain. Thus, standard optical characterization methods like Photoluminescence (PL) and Raman spectroscopy, which commonly provide such information, can lack the spatial resolution to resolve these variations. Here, electrical atomic force microscopy (AFM) methods with in-situ illumination at different wavelengths deliver nanoscale information on the impact of layer thickness, changes in substrates interactions and local strain onto the material's optoelectronic response.
In our study, we demonstrate the capability of photo-Kelvin probe force microscopy (pKPFM) to capture local photo-potential in mono- and few-layer WS2 and correlate PL spectroscopy. Furthermore, we investigate the impact of substrates on the local charge carriers.
Keywords: WS₂; Exciton; Photoluminescene; photo-KPFM; Substrate