La、Yb掺杂AlN的光电特性和磁性的第一性原理研究

First principles study of the photoelectric properties and magnetism of La and Yb doped AlN

为了探索AlN在光电器件的潜在应用,基于密度泛函理论,采用第一性原理计算了本征AlN和稀土元素La、Yb掺杂AlN体系的光电特性和磁性。计算结果表明:本征AlN的带隙为6.060 eV。掺入La和Yb后都在导带底产生了杂质能级,使得电子从价带到导带所需的激发能量更低,有利于光学跃迁,从而改善AlN的光学性能。Yb掺杂后自旋向上和自旋向下的价带发生了劈裂,说明Yb掺杂后产生了磁性。La、Yb替位掺杂AlN后,光吸收带边向左往低能方向移动,发生了红移现象。掺杂La和Yb后AlN体系的静态介电常数由4.63分别增大为5.14、280.44,说明掺杂之后增强了体系耐高压特性;静态折射率则由2.12分别增大为2.26、17.06,改善了AlN的光学性质。

To explore the potential application of AlN in optoelectronic devices,based on density functional theory,the photoelectric properties and magnetic properties of intrinsic AlN and rare⁃earth elements La,Yb doped AlN sys⁃tem were calculated by first principles.The calculation results showed that the intrinsic AlN band gap was 6.060 eV.After the addition of La and Yb,impurity levels were generated at the bottom of the conduction band,which makes the excitation energy required for electrons to be brought from valence to the conduction band lower,which is conducive to the optical transition and improves the optical properties of AlN.Spin⁃up and spin⁃down valence bands split after Yb doping,indicating that Yb doping produces magnetism.When La and Yb substitution were doped with AlN,the edge of the absorption band moved to the left in the direction of low energy,and the redshift phenomenon occurred.After doping La and Yb,the static dielectric constant of the AlN system increased from 4.63 to 5.14 and 280.44,respectively,indicating that doping enhances the high voltage resistance of the system.The static refractive index increased from 2.12 to 2.26 and 17.06 respectively,which improves the optical properties of AlN.