Al_xGa_(1-x)Sb三元混晶电子结构和光学性质的第一性原理研究

First-principles study on electronic structures and optical properties of Al_xGa_(1-x)Sb ternary mixed crystals

为更加深入地了解混晶效应对半导体材料性质的影响,采用基于密度泛函理论的第一性原理平面波超软赝势方法,研究了闪锌矿结构三元混晶Al_xGa_(1-x)Sb(0≤x≤1)的电子结构和光学性质。通过对不同Al组分三元混晶Al_xGa_(1-x)Sb的总能量与形成能的计算比较,获得了稳定结构Al_xGa_(1-x)Sb的晶格常数,同时计算了Al_xGa_(1-x)Sb在不同Al组分的电子结构,讨论了带隙、能带结构和态密度等随Al组分的变化规律。计算结果表明:混晶的带隙随Al组分的增加而增大;能带结构由下、中、上价带和导带4个部分构成,给出了晶格常数、带隙随Al组分变化的拟合公式;计算了Al_xGa_(1-x)Sb材料的复介电函数、高频/静态介电常数和吸收光谱随Al组分的变化情况,发现高频与静态介电常数随Al组分增加而降低,吸收光谱发生蓝移,与实验观测值和其他的理论结果相符。

To better understand the effect of mixed crystal effect on semiconductor material properties,the electronic structure and optical properties of ternary mixed crystal AlxGa1-xSb（0≤x≤1）were investigated based on the density functional theory research by using plane-wave ultrasoft pseudo-potential method.By calculating the total energy and formation energy of AlxGa1-xSb under different Al component,the lattice constant of AlxGa1-xSb with stable structure was obtained.At the same time,the electronic structures of AlxGa1-xSb in different Al components were calculated,and the variation law of band gap,band structure and density of states with Al component was discussed.The results show that the bandgap of AlxGa1-xSb increases with the increase of Al component,and the band structure consists of 4 parts including the lower,the middle,the upper valence band and the conduction band.The fitting formula of lattice constant and band gap with Al component is given.Finally,the complex dielectric function,high-frequency dielectric constant,static dielectric constant and absorption spectra of AlxGa1-xSb material for different Al component were calculated.It is found that the high-frequency and static dielectric constant decreases with the increase of Al component,and the absorption spectra shifts blue,which agrees with the experimental and other theoretical results.