SKM 2023 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 33: Poster II

HL 33.1: Poster

Mittwoch, 29. März 2023, 17:00–19:00, P1

Pump-probe spectroscopy on a MoSe2 monolayer — •Max Wegerhoff and Stefan Linden — Physikalisches Institut, Universität Bonn, Nussallee 12, 53115 Bonn, Germany

TMDC monolayers are atomically thin semiconductor materials, which, due to their reduced dimensionality and crystal structure, possess unique optical properties. In particular, they host bound electron-hole pairs, so-called excitons, with binding energies of several 100 meVs.

Here, we report on pump-probe spectroscopy on excitons in a MoSe2 monolayer encapsulated in h-BN. We use spectrally broad probe pulses and a spectrometer to measure the transient differential reflectivity spectra. Based on a mode-locked Ti:Sa laser, a temporal resolution of down to 400fs is achieved. A frequency-doubled OPO can be used to generate non-resonant pump pulses in the visible wavelength range. Furthermore, probe pulses with a bandwidth of up to 70nm can be generated via supercontinuum generation in a photonic crystal fiber. The experiments are performed at 4K in a helium-flow cryostat.

Within the first few picosecond after the pump pulse, we observe a blueshift of the exciton resonance. This shift depends on the wavelength of the pump pulses as well as the polarization of the pump- and probe pulses. Further experiments with an electrically gated heterostructure to control the doping of the monolayer are in progress.