Study the energy landscape of a 2D-based device in operando using spatially resolved X-ray photoemission spectroscopy
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Tutelle : Institut des NanoSciences de Paris (INSP) -- Sorbonne Université, CNRS
Mots clés : Experimental et Stage M2
Gratification : Oui
Page des stages de(s) l'équipe(s) : Physico-chimie et dynamique des surfaces
Description du stage
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Résumé / summary
Nowadays, the family of two-dimensional (2D) materials expands vastly beyond graphene, including semiconductive materials as transition metal dichalcogenides (TMDs) of the MX2 type (M = Mo, W; X = S, Se, Te). Due to their relatively small band gap (1.2-2.2 eV) and the atomically flat surface, free of dangling bonds in this material, we can easily obtain an ambipolar transistor operation under an electric field by generating a p-n junction. This a quite important property of TMDs making them promising candidates for a variety of opto-electronic devices. However, different from a conventional p-n junction, in the field induce one, donors or acceptors are absent. Since their densities determine many fundamental parameters of conventional p-n junction, such as the built-in potential and the depletion region length, these parameters are basically unknown from field induced p-n junction.
This internship project aims to go a step further in the understanding of TMD p-n junction by probing directly the electronic structure of this device in operando (i.e., during device operation) using spatially resolved X-ray photoemission spectroscopy at the synchrotron facility (spatial resolution below the μm – ANTARES beamline -SOLEIL synchrotron)1–3. The device that will be studied is a dual gate transistor (Figure 1 (a)) where the two gates are used to create a planar p-n junction in the TMD nanoflake by generating an electrostatic doping.
During the internship the candidate will be in charge of TMDs flake exfoliation and transfer (using a 2D transfer system) with micrometer precision across the device channel (Figure 1(b)), device characterization at the laboratory with AFM, PL, Raman, and electrical measurements before to perform operando spatial resolved X-ray photoemission measurement at the synchrotron facility.
1 Cavallo, M. et al. Nanoscale 15, 9440–9448 (2023)
2 Cavallo, M. et al. Nano Lett. 23, 1363–1370 (2023)
3 Cavallo, M. et al. Adv. Funct. Mater. 2300846 (2023)