Cu/Mg掺杂AlN的电子结构和光吸收研究

Electronic structures and optical absorption of Cu/Mg doped AlN

采用平面波超软赝势和广义梯度近似的第一性原理计算方法,对本征Al N和掺杂体系Al N∶Cu,Al N∶Mg,Al N∶Cu-Mg的超晶胞进行了几何优化,计算了它们的电子结构、能带、态密度、磁矩及光学性质等。结果表明,Al N∶Cu,Al N∶Mg均表现为100%自旋注入,材料均具有半金属性质,其中Cu掺杂体系的半金属性更稳定;Al N∶Cu-Mg共掺体系在能隙深处产生杂质带,具有金属性,改善了材料的高阻抗现象。研究发现Cu掺杂体系的磁矩最大,Cu-Mg共掺体系较Mg单掺的净磁矩有所减少。进一步分析光学性质发现,杂质离子的引入使得低能区的介电函数和复折射率函数出现明显的峰值,其中共掺体系的峰值最大,明显增强了体系对低频电磁波的吸收。

The geometrical structures of Al N,Al N∶ Cu,Al N∶ Mg,and Al N∶ Cu-Mg 32-atom super-cell was optimized by using the first principle density functional theory based on the full potential linearized augumented plane wave method and generalized gradient approximation. Electronic structure,energy band,density of states,optical properties and magnetic moments were calculated and discussed in detail. The results show that the Al N: Cu,Al N: Mg both were 100%spin injection and have half metal material properties. The Cu doped system has more stable half metal properties. Al N:Cu- Mg system produce the spin polarization impurity band in the deep energy gap,with metal attributes,improving the electrical conductivity of the system. The system of Cu doped Al N have maximum of magnetic and the system of Cu-Mg co-doped have minimum of magenetic. It was found that systerm of the introduction of impurity ions has obvious peak value in the complex refractive index and dielectric function function in low-energy by further analysis of the optical properties,which strengthen the absorption of low frequency electromagnetic wave.