MoSi_(2)N_(4)的本征点缺陷以及掺杂特性的第一性原理计算

First-principles calculation of intrinsic point defects and doping performance of MoSi_(2)N_(4)

新兴二维材料MoSi_(2)N_(4)因其卓越的半导体性能,包括出色的环境稳定性和高载流子迁移率而受到相当多的关注.然而,半导体中的本征缺陷往往不可避免并且会显著影响器件性能.本文使用密度泛函理论计算并分析了MoSi_(2)N_(4)中本征点缺陷的性质及其产生的影响.首先确认了该材料物理性质与目前实验数据的一致性,之后通过计算12种本征缺陷的形成能,发现钼替硅型反位缺陷(Mo_(Si))在所有本征缺陷中占主导地位.在整体电荷保持中性的约束条件下,通过自洽费米能级计算,本文发现仅仅引入本征缺陷的MoSi_(2)N_(4)会表现出本征特征,这体现了其作为半导体器件材料的潜力,然而该本征性质与在生长过程中观察到的二维MoSi_(2)N_(4)的p型特征相矛盾.而在后来的缺陷浓度计算中,发现对于MoSi_(2)N_(4)用适当的杂质进行掺杂,可以实现n型和p型半导体特征,且本征缺陷的补偿效应很弱.这表明在生长过程中MoSi_(2)N_(4)的p型特征可能是由于非平衡生长条件下引入的杂质或硅空位缺陷造成的.本工作不仅展示了MoSi_(2)N_(4)在半导体器件应用上的潜力,还为未来该材料缺陷机理的研究提供了数据支撑.

MoSi_(2)N_(4) 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_(2)N_(4).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_(Si))defect dominates in all intrinsic defects.Under the constraint of overall charge neutrality,self-consistent Fermi level calculations reveal that MoSi_(2)N_(4) 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_(2)N_(4).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_(2)N_(4) 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_(2)N_(4) in semiconductor devices but also provide valuable guidance for future studying the defect mechanisms of this material.