Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 29: Poster: 2D Materials
O 29.29: Poster
Dienstag, 19. März 2024, 12:30–14:30, Poster A
SNOM of lateral TMDC heterostructures — •Philipp Schwendke1, Samuel Palato1, and Julia Stähler1,2 — 1Humboldt-Universität zu Berlin — 2Fritz-Haber-Institut der MPG
Semiconductor heterojunctions are the basis of many modern devices such as transistors, LEDs, and photovoltaics. 2D semiconductors such as TMDCs promise similar applications at an atomic level, which is why their interfaces are of particular interest. A variety of useful heterojunction properties have been realized, such as the photovoltaic effect and current rectification. While stacked van der Waals heterostructures ideally offer spatially homogeneous properties, lateral heterojunctions feature a lateral charge transfer following the band alignment across an interface region. Here, the charge carrier energy levels and lifetimes vary spatially in a way that is to date not fully understood. To explore said properties, we use scanning near-field optical microscopy (SNOM) combined with a femtosecond laser to investigate electron dynamics at ultrafast time scales with nm spatial resolution. Using previously introduced quadrature-assisted discrete (QUAD) demodulation, we are able to perform SNOM with a low repetition rate laser producing highly tunable fs laser pulses. QUAD demodulation is compatible with known methods of noise reduction, e.g. pseudo-heterodyne or balanced detection, and straightforward to extend into a pump-probe scheme for time resolution. This makes time-resolved SNOM an ideal candidate for the investigation of electronic properties of lateral heterojunctions.
Keywords: scanning near-field microscopy (SNOM); lateral heterojunctions; electron dynamics; transition metal dichalcogenides (TMDC)