Resonance Raman scattering on graded-composition WxMo1–xS2 alloy with tunable excitons.

Exciton–phonon interactions strongly affect photocarrier dynamics in two-dimensional materials. Here we report on resonant Raman experiments based on a graded composition W_xMo_1–xS₂ alloy with tunable exciton energy without changing the energy of excitation laser. The intensities of the four most pronounced Raman features in the alloy are dramatically enhanced due to the resonance derived from the energy of B exciton shifting to the vicinity of the energy of excitation laser with an increase in W composition x. Specifically, through the resonance peak shift, absorption spectra and PL emission spectra under different excitation power, we conclude the resonance Raman is related to the exciton emission process. Our study extends the resonant Raman study of two-dimensional materials, which is expected to obtain deeper understanding of the excitonic effects in two-dimensional semiconductor materials. [ABSTRACT FROM AUTHOR]