An improved method for controllable growth of monolayer WSe2 and its optical characterization

Abstract Due to the van der Waals interaction between the transition metal sulfide layers, it can be stripped into a single atomic layer, and tungsten diselenides(WSe 2 ) as one of the typical p-type semiconductors has become a research hotspot. WSe 2 thin flakes have been successfully prepared by chemical vapor deposition(CVD) methods, but the synthesis conditions of WSe 2 are usually highly sensitive and difficult to control, which makes it difficult to grow monolayer WSe 2 with good lattice quality in a large area. Here, we use a new CVD growth method to improve the product quality, through the combination of reverse gas flow and rapid heating method to improve the nucleation and lattice quality of WSe 2 .This work will systematically study the effects of key growth conditions, focus on elucidating the growth mechanism, and optimize the growth parameters. In order to verify the preparation of monolayer and multi-layer WSe 2 thin flakes with good lattice quality. WSe 2 thin flakes were characterized by optical microscope, atomic force microscope, Raman spectrum and photoluminescence (PL) spectrum. Moreover, monolayer WSe 2 and multi-layer WSe 2 can be distinguished by Raman test and fluorescence spectrum test, and they have different characteristic peaks. We can judge whether the material is monolayer by observing the peak position.