Síntese por CVD de WS2 e WSe2 e quantificação de defeitos estruturais via Espectroscopias Raman e de Fotoluminescência

Abstract

The last few years, transition metal dichalcogenides (TMDs) have been widely studied due to their unusual optoelectronic properties. Recently, the study of defects in these materials allows the application in semiconductor devices, since defects can disturb the crystal lattice locally, leading to some kind of electronic band engineering. In this work, we synthesized monolayers of WS2 and WSe2 by chemical vapor deposition (CVD), and studied the sizes and shapes of these materials as a function of the amount of H2 present in the synthesis. We carried out a study of punctual defects in monolayers of WS2, by bombarding the crystals with a He focused ion beam. We verified the existence of some Raman bands and new electronic transitions, present in the photoluminescence spectra, activated by defects. The same punctual defect model that allows predicting the crystallinity of graphene and molybdenum TMD was employed to visualize when WS2 begins to become amorphous. Thus, this work enables the identification of defects in tungsten TMDs, which seems to be a promising material for the semiconductor industry.