La掺杂3C-SiC电子结构和光学性质的第一性原理研究

采用基于密度泛函理论的第一性原理计算方法,对未掺杂及稀土材料La掺杂3C-SiC的电子结构和光学性质进行理论计算.计算结果表明,La掺杂引起3C-SiC晶格体积增大,掺杂体系能量更小,掺杂体系的结构更稳定;未掺杂3C-SiC是直接带隙半导体,其禁带宽度为1.406 eV,La掺杂后带隙宽度下降为1.161 eV,La掺杂3C-SiC引入了3条杂质能级,能量较高的1条杂质能级与费米能级发生交叠,另外2条杂质能级都在费米能级以下价带顶之上,La掺杂引起3C-SiC吸收谱往低能区移动,未掺杂3C-SiC的静态介电常数为2.66,La掺杂引起静态介电常数增加为406.01,La掺杂3C-SiC是负介电半导体材料.

First principles study of electronic structures and optical properties of La doped 3C-SiC

The electronic structures and optical properties of undoped and La doped 3C-SiC were calculated by the first principle calculation method based on density functional theory. The results show that La doping increases the lattice volume of 3C-SiC, the energy of the doped system is smaller, and the structure of the doped system is more stable. Undoped 3C-SiC is an indirect bandgap semiconductor, whose gap width is 1.406 eV, and La doped bandgap width is reduced to 1.161 eV, La-doped 3C-SiC introduces three impurity levels, and one impurity level with higher energy overlaps with the Fermi level, and the other two impurity levels are above the valence band below the Fermi level. La doping causes 3C-SiC absorption spectrum to move to low energy region. The static dielectric constant of undoped 3C-SiC was 2.66, and the static dielectric constant was increased to 406.01 by La doping, La-doped 3C-SiC is a negative dielectric semiconductor material.