(La,Y)掺杂AlN的电子结构和光学性质的第一性原理研究

First-Principles Study on Electronic Structure and Optical Properties of(La,Y)-Doped AlN

采用基于密度泛函理论的平面波超软赝势方法对纯AlN、(La,Y)单掺杂以及La-Y共掺杂AlN超胞进行几何结构优化,计算了稀土元素(La,Y)掺杂前后体系的能带结构、态密度和光学性质。结果表明:未掺杂的AlN是直接带隙半导体,带隙值为E_(g)=4.237 eV,在费米能级附近,态密度主要由Al-3p、N-2s电子轨道贡献电子,光吸收概率大,能量损失较大;掺杂后使得能带结构性质改变,带隙值降低,能带曲线变密集,总态密度整体下移;在光学性质中,稀土元素掺杂后均提高了静态介电常数、光吸收性能,增强了折射率和反射率,减小了电子吸收光子概率及能量损失;其中La-Y共掺体系变化得较为明显。

The geometry of pure AlN,(La,Y)single-doped and La-Y co-doped AlN superlattices was optimized by the plane wave ultrasoft pseudopotential method based on density functional theory.The band structure,density of states and optical properties of the system before and after rare earth elements(La,Y)doping were calculated.The results show that the undoped AlN is a direct band gap semiconductor,and the band gap value is E_(g)=4.237 eV.The density of state is mainly contributed by electron orbitals of Al-3p and N-2s.After doping,the band structure property is changed,the band gap value reduces,the band curve is denser,and the total density of states moves down as a whole.In terms of optical properties,the doping of rare earth elements improves the static dielectric constant and light absorption performance,enhances the refractive index and reflectivity,and reduces the probability of electron absorption photon and energy loss.Among them,La-Y co-doped system changes obviously.