Study on the electron dynamics of MoS2 under ultraviolet femtosecond laser irradiation

Abstract

As a promising two-dimensional (2D) material, MoS₂ exhibits considerable potential for applications in miniaturized optoelectronic devices. Although extensive research has been conducted on laser processing techniques for patterning or thinning MoS₂, studies on the interaction mechanisms between lasers and MoS₂ relatively limited. This paper employs first-principles methods based on time-dependent density functional theory (TDDFT) to systematically investigate the excited-state properties of MoS₂ under ultraviolet laser irradiation, which enhances our understanding of the interaction processes between femtosecond lasers and 2D materials. The study explores the impact of laser intensity on energy deposition, photoinduced current, and the distribution of electron-hole pairs. The results indicate that the modulus of the optical conductivity decreases rapidly with increasing laser intensity, highlighting a more pronounced saturation absorption effect in the current. Additionally, a phase transition was observed at a laser intensity of 5×10¹² W/cm², providing new insights into laser-induced phase transitions. By analyzing the spatiotemporal distribution of charge carriers, the study elucidates the mechanisms of charge carrier transport. These simulation results establish a foundation for optimizing laser processing techniques for MoS₂.