The atomic-scale mechanisms by which intrinsic defects influence charge carrier dynamics in monolayer MoSi2N4 remain poorly understood in current studies of this emerging two-dimensional material. By combining first-principles density functional theory (DFT) and ab initio nonadiabatic molecular dynamics (NAMD) simulations, we investigated the static properties and carrier dynamics of MoSi2N4 monolayers with and without intrinsic defects. MoSi2N4 reveals strong band dispersion near the conduction band minimum, with weak coupling between the K-valley states and other states, leading to delayed electron relaxation and suppressed energy dissipation. Notably, the MoSi defect (Mo substituting Si) induces a pronounced spin-polarized lifetime contrast, where spin-down carriers exhibit extended lifetimes in comparison to those in pristine MoSi2N4. In contrast, an internal N vacancy introduces deep defect states that significantly accelerate electron–hole recombination. The SiMo defect (Si substituting Mo) contributes negligibly to defect-assisted recombination. These findings provide new insights for designing high-performance MoSi2N4-based optoelectronic and nanoelectronic devices.
You et al. (Mon,) studied this question.