N空位、Ga空位对GaN∶Mn体系电磁性质和光学性质影响的第一性原理研究

First-principles study of the effects of GaN∶Mn with N vacancy and Ga vacancy on electronic structures,ferromagnetism and optical properties

基于密度泛函理论的第一性原理平面波超软赝势法分别计算了VGa和VN距掺入Mn原子为近邻、次近邻、远近邻各3种情况下GaN体系的电子结构和光学性质,分析比较了空位的不同位置对Mn掺杂GaN体系磁性的影响。计算结果表明,Mn掺杂会导致GaN体系带隙增大且体系表现为半金属铁磁性;VN的存在会增强缺陷复合物体系的铁磁性,且随着VN相对杂质Mn距离越近,体系总磁矩增加;而VGa的存在会降低缺陷复合物体系的铁磁性,且随Ga空位相对杂质Mn距离越近,体系总磁矩减少。不同位置的VGa和VN均会导致缺陷复合物体系主吸收峰和光吸收边相对于单Mn掺杂而言向低能方向移动,出现红移现象。

The electronic structures and optical properties of Ga vacancy and N vacancy from the incorporation of Mn atoms doping as nearest neighbor,next nearest neighbor and far neighbor each of the three cases GaN sys-tems were calculated by using plane wave ultra-soft pseudo-potential method based on density functional theory. This article analyzed and compared the effects of different positions of vacancies on the performance of magnetic properties of Mn doped GaN.The results indicate that the band gap becomes wider after Mn doped GaN,and it shows half metallic ferromagnetism.N vacancies enhance the ferromagnetism of Mn doped GaN systems and the total magnetic moment of the doped systems increases with the decrease of the N vacancy away from Mn impu-rity.However,Ga vacancies reduce the ferromagnetism of Mn doped GaN systems and the total magnetic mo-ment of the doped systems decreases with the reduction of the Ga vacancy away from Mn impurity.Further-more,the main absorption peaks and absorption edge move towards a lower energy region in all cases of vacan-cies of Mn doped systems,which shows a red shift phenomenon.