Gate-Tunable Resonant Raman Spectroscopy of Bilayer MoS₂

The gate-tunable phonon properties in bilayer MoS₂ are shown to be dependent on excitation energy. Raman intensity, Raman shift, and linewidth are affected by resonant excitation, while a nonresonant laser does not influence the intensity significantly. The gate-dependent Raman shift of A_1g mode (either blue-, red-, or no-shift) is a result of the combined effect of antibonding electron and resonant-related decoupling effect. Although the decoupling effect cannot be directly measured due to the resonant background, it can be indirectly and qualitatively probed by observing A_1g mode. This study on gate-tunable resonant Raman spectroscopy has clarified the influence of carrier doping on phonon properties and demonstrates a new degree of freedom in manipulating phonons in 2D material systems.