二维g-AlN材料中n型掺杂探索:基于第一性原理的带电缺陷计算

Exploration of n-type doping in two-dimensional AlN materials:Calculation of charged defects based on first principles

电荷转移能级和缺陷形成能的计算对探索半导体材料的n型和p型掺杂效率具有重要的指导意义.基于第一性原理方法,结合二维带电缺陷计算理论,系统计算了二维氮化铝中四种(C_(Al),Si_(Al),Ge_(Al),Sn_(Al))可能的n型掺杂体系的结构、磁学、电学以及缺陷性质.结果表明,四种体系的最稳定价态均为+1价和0价,Sn_(Al)具有较深的施主能级,不具备为二维g-AlN提供n型载流子的条件,而C_(Al),Si_(Al),Ge_(Al)表现为浅能级施主特性,均能在一定条件下成为理想的施主杂质,其中Si_(Al)具有最浅的施主特性以及最低的缺陷形成能,因而是二维g-AlN中实现n型掺杂的首选掺杂剂.另外,在p型二维g-AlN中,四种掺杂原子都会成为有效的空穴捕获中心,严重降低p型载流子导电率.研究数据将会为实验上实现二维g-AlN n型掺杂提供理论解释和指导.

The calculation of charge transition energy level(CTL)and defect formation energy are of significance to explore potential n-type or p-type doping in semiconductor materials.Based on the first principle method and combined with the theory of two-dimensional(2D)charged defect calculation,the structural,magnetic,electronic and defect properties of four possible n-type doping systems in two-dimensional g-AlN(C_(Al),Si_(Al),Ge_(Al),Sn_(Al))were systematically calculated.The results showed that the most stable charge states(MSCSs)for all defect system are+1 and 0 charge states,Sn_(Al)would not contribute n-type carriers in 2D g-AlN due to its deep donor defect level.In contrast,C_(Al),Si_(Al)and Ge_(Al)which are characterized as shallow donor level will contribute significant n-type carriers in 2D g-AlN under certain conditions.Additionally,as Si_(Al)has the shallowest donor characteristics and the lowest defect formation energy,it is the most preferred n-type dopant in 2D g-AlN.In addition,in p-type 2D g-AlN,all the four kinds of doped atoms will become effective hole capture centers and thus seriously reduce the conductivity of p-type carriers.Our research will provide theoretical explanation and certain guidance for the experimental realization of n-type doping in 2D g-AlN.