First-principles calculation of intrinsic point defects and doping performance of MoSi<sub>2</sub>N<sub>4</sub>

Abstract

MoSi<sub>2</sub>N<sub>4</sub> is an emergent two-dimensional (2D) material, which has received much attention because of its excellent performance over semiconductors, including excellent environmental stability and high carrier mobility. However, the formation of intrinsic defects in semiconductors is often inevitable and can significantly affect device performance. By using density functional theory (DFT), we analyze the properties and effects of intrinsic point defects in MoSi<sub>2</sub>N<sub>4</sub>. We first confirm the consistency of our results with current experimental data. After that, the formation energy values of twelve native defects reveal that the antisite defect of molybdenum substituting for silicon (Mo<sub>Si</sub>) defect dominates in all intrinsic defects. Under the constraint of overall charge neutrality, self-consistent Fermi level calculations reveal that MoSi<sub>2</sub>N<sub>4</sub> with only intrinsic defects exhibits intrinsic characteristics, highlighting its potential as a semiconductor device material. However, this intrinsic nature contradicts the p-type characteristics observed in two-dimensional MoSi<sub>2</sub>N<sub>4</sub>. In the subsequent defect concentrations, we find that both n-type and p-type behavior can be easily realized by doping appropriate impurities without being compensated by native defects. This suggests that the p-type characteristics of MoSi<sub>2</sub>N<sub>4</sub> during growth may result from p-type impurities introduced under non-equilibrium growth conditions or silicon vacancy defects. Our findings not only demonstrate the potential applications of MoSi<sub>2</sub>N<sub>4</sub> in semiconductor devices but also provide valuable guidance for future studying the defect mechanisms of this material.