Raman spectroscopy of 2D MoS2 on Ti3C2 MXene: the substrate effect

Abstract

We use Raman spectroscopy to study the substrate effect of Ti₃C₂ MXene on the lattice vibrational modes of MoS₂. We observed redshifts in the fingerprint peaks of MoS₂, and explained the shifts based on their vibrational nature. The shift in the in-plane E¹_2g mode is attributed to the strain effect, and the softened A_1g mode associated with the out-of-plane vibration is caused by electron doping. In addition to monolayer MoS₂, we show that the modulation from Ti₃C₂ MXene is also present in few-layer and bulk MoS₂. Furthermore, we demonstrate that the laser-induced shift occurs even at low excitation power. Our results indicate that a detailed power-dependent measurement is indispensable for extracting the pure substrate effect from Raman spectroscopy.