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Zusammenfassung:
Synthesis of large-area atomically thin transition metal dichalcogenides (TMDs) on diverse substrates is of central importance for large-scale fabrication of flexible devices and heterojunction-based devices. In this work, we successfully synthesized a large area of highly crystalline MoSe2 atomic layers on SiO2/Si, mica and Si substrates by using a simple atmospheric pressure chemical vapor deposition (CVD) method. Atomic Force Microscopy (AFM) and Raman spectroscopy reveal that the as-grown ultrathin MoSe2 layers change from a single layer to a few layers. Photoluminescence (PL) spectroscopy
demonstrates that while the multi-layer MoSe2 shows weak emission peaks, the monolayer has a much stronger emission peak at ~ 1.56 eV, indicating the transition from an indirect to direct bandgap. Analysis based on transmission electron microscopy (TEM) confirms the single-crystallinity of MoSe2 layers with a hexagonal structure. In addition, photoresponse performance of photodetectors based on monolayer MoSe2 was studied for the first time. The devices exhibit a rapid response of ~ 60 ms and a good photoresponsivity of ~ 13 mA/W (a 532 nm laser with the intensity of 1 mW/mm2 and a 10 V bias), suggesting that the monolayer MoSe2 is a promising material for photodetection application.
