Photoluminescence and Raman mapping characterization of WS2 monolayers prepared using top-down and bottom-up methods

Abstract

Two kinds of tungsten disulfide (WS₂) monolayers, respectively prepared using top-down and bottom-up approaches, were studied with Raman and photoluminescence (PL) mapping techniques. By mapping the intensities of the two characterized phonon modes of WS₂, the monolayer region can be quickly selected. Such selection by mapping the intensities is more conclusive than by comparing the small shift in phonon peak position. Also, PL mapping yields more information regarding the uniformity and quality of the monolayers than does Raman mapping. We also show that the focused laser may cause substantial damage to the crystal lattice of monolayers for long-duration mappings.