Luminescence Enhancement and Raman Characterization of Vanadium-Doped WSe2 Monolayers

Monolayer Tungsten diselenide (WSe₂) is a direct band gap semiconductor that has good luminescence properties which are of great interest for optoelectronics applications. In this study, the effect of vanadium (V) incorporation in WSe₂ monolayers grown by chemical vapor deposition (CVD) was ivestigated by a multi-technique approach. Our results indicates that lightly V-doped WSe₂ exhibits an enhanced photoluminescence (PL) response when compared to pristine WSe₂ (up to 250%) and strongly quenched PL signal for highly doped samples. Resonance Raman spectroscopy measurements were performed to study the disorder effects due to the presence of V in the lattice. It was possible to observe the activation of the defect-related LA(M) mode and the evolution of the 2LA(M) and A(M) modes as a function of V concentration. Further, complementary, X-ray photoelectron spectroscopy (XPS) and high-resolution scanning transmission electron microscopy (HR-STEM) measurements were performed to investigate the strucutral and chamical changes in the samples.