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Subject: crystals × WGL Institute: IPHT ×

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    Controlled growth of transition metal dichalcogenide monolayers using Knudsen-type effusion cells for the precursors
    (Bristol : IOP Publishing, 2019) George, Antony; Neumann, Christof; Kaiser, David; Mupparapu, Rajeshkumar; Lehnert, Tibor; Hübner, Uwe; Tang, Zian; Winter, Andreas; Kaiser, Ute; Staude, Isabelle; Turchanin, Andrey
    Controlling the flow rate of precursors is essential for the growth of high quality monolayer single crystals of transition metal dichalcogenides (TMDs) by chemical vapor deposition. Thus, introduction of an excess amount of the precursors affects reproducibility of the growth process and results in the formation of TMD multilayers and other unwanted deposits. Here we present a simple method for controlling the precursor flow rates using the Knudsen-type effusion cells. This method results in a highly reproducible growth of large area and high density TMD monolayers. The size of the grown crystals can be adjusted between 10 and 200 μm. We characterized the grown MoS2 and WS2 monolayers by optical, atomic force and transmission electron microscopies as well as by x-ray photoelectron, Raman and photoluminescence spectroscopies, and by electrical transport measurements showing their high optical and electronic quality based on the single crystalline nature.
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    Comparative Analysis of Raman Signal Amplifying Effectiveness of Silver Nanostructures with Different Morphology
    (Basel : MDPI, 2022) Yakimchuk, Dzmitry V.; Khubezhov, Soslan A.; Prigodich, Uladzislau V.; Tishkevich, Daria I.; Trukhanov, Sergei V.; Trukhanov, Alex V.; Sivakov, Vladimir; Kaniukov, Egor Y.
    To increase the attractiveness of the practical application of molecular sensing methods, the experimental search for the optimal shape of silver nanostructures allowing to increase the Raman cross section by several orders of magnitude is of great interest. This paper presents a detailed study of spatially separated plasmon-active silver nanostructures grown in SiO2/Si template pores with crystallite, dendrite, and “sunflower-like” nanostructures shapes. Nile blue and 2-mercaptobenzothiazole were chosen as the model analytes for comparative evaluation of the Raman signal amplification efficiency using these structures. It was discussed the features of the structures for the enhancement of Raman intensity. Finally, we showed that silver crystals, dendrites, and “sunflower-like” nanostructures in SiO2/Si template could be used as the relevant materials for Raman signal amplification, but with different efficiency.