Ge掺杂AlN电子和光学性质的第一性原理计算  

First-Principles Calculations of Electronic and Optical Properties of Ge Doped AlN

作　　者：罗强[1] 马智炜 蒋冠臻 邹江峰 邱毅[1] LUO Qiang;MA Zhiwei;JIANG Guanzhen;ZOU Jiangfeng;QIU Yi(College of Science Southwestern Petroleum University,Chengdu,Sichuan 610500,China)

机构地区：[1]西南石油大学理学院,四川成都610500

出　　处：《计算物理》2022年第5期609-616,共8页Chinese Journal of Computational Physics

基　　金：国家自然科学基金(51875091);南充市市校科技战略基金(SXHZ008)资助项目。

摘　　要：基于密度泛函理论(DFT)的第一性原理方法,用Ge原子分别替代纤锌矿AlN超晶胞中Al、 N原子,得到其结构、电子及光学性质。结果表明:掺杂后结构发生了明显的改变,两种方式的掺杂都使得AlN的晶格常数、体积和沿c轴方向的键长增加,且晶格常数变化满足维加德(Vegard)定理;Ge原子替换Al原子形成能为5.41 eV, Ge原子替换N原子形成能为5.58 eV,两种掺杂方式体系稳定性都低于纯AlN;掺杂并未引入磁性,前者引入施主杂质能带,且杂质能带进入价带,变为负能隙金属,后者引入受主杂质能带,禁带宽度为0.910 eV,两者均远小于本征AlN的禁带宽度4.040 eV,前者导电性显著提高,后者导电性可能提高;研究发现两种方式掺杂复折射率函数的虚部在低能区都近似不再为0,表明两种掺杂都加强了AlN材料对低频电磁波的吸收能力;前者介电函数虚部在低能区出现了新的波峰,长波吸收能力更强,后者在低能区未出现明显波峰,能量损失均减少。With the first-principles method of density functional theory(DFT), the structure, electronic and optical properties of wurtzite AlN supercells were obtained by substituting Ge atoms for Al and N atoms, respectively. It shows that the structure changes obviously with doping. The lattice constants, volume and bond length along c-axis of AlN increase in both doping methods, and the lattice constants change satisfies Vegard′s theorem. Forming energy of Ge atom substituted for Al atom is 5.41 eV, and that of Ge atom substituted for N atom is 5.58 eV. Stability of the doped systems is lower than that of pure AlN. Magnetism is not introduced in both doping methods, but the former introduces donor impurity band and an impurity band enters valence band, which makes it becomes negative energy gap metal. The latter introduces acceptant impurity band with a band gap of 0.910 eV. Both gaps are much smaller than intrinsic AlN band gap of 4.040 eV. Conductivity of the former is significantly improved, while conductivity of the latter may be improved. It is found that imaginary part of the complex refractive index function after doping in two ways is approximately no longer to 0 in the low energy region, indicating that the absorption ability of AlN materials to low frequency electromagnetic wave is enhanced in both doping ways. Imaginary part of dielectric function of the former has a new peak in low energy region, while the latter has no obvious peak in that region. The former has a stronger absorption capacity of long wave. The energy loss is reduced in both.

关 键 词：Ge掺杂AlN 第一性原理 电子性质 光学性质 

分 类 号：O469[理学—凝聚态物理]