Substrate proximity doping induced optical properties and ultrafast carrier dynamics modulation in monolayer MoS2

As the support structure that has the closest contact with two-dimensional (2D) materials, the substrate can significantly affect the optical and electrical properties of 2D materials, and is expected to become an effective regulatory approach to meet different device requirements. Here we confirm the proximity doping effect of the substrate on 2D materials through photoluminescence (PL), absorption, Raman and XPS spectra. Due to the proximity doping effect of the conductive substrate, the absorption and PL properties of MoS2 will be affected, which makes their optical behavior dominated by negatively charged excitons rather than excitons. Furthermore, through micro-area nonlinear optical and transient absorption tests, it was proved that this effect can also affect the recombination process of non-optically active excitons and ultrafast carriers formed by band nesting. As 3an effective way to regulate the optical properties of 2D materials, this method is expected to have a profound impact on the optoelectronic properties of 2D materials and optoelectronic devices.