Co掺杂6H-SiC的第一性原理研究

First-principles study of Co-doped 6H-SiC

此文用第一性原理密度泛函理论(DFT)的广义梯度近似(GGA)的平面波赝势法(PBE),计算了未掺杂及Co替位Si掺杂的6H-SiC体系的电子结构与光学特性,获得了Co掺杂将导致6H-SiC由带隙为2.016 eV的间接带隙半导体变成带隙为0.071 eV的p型半导体,且有磁性;掺杂后能带结构中出现由Co的3d能级造成的杂质能级;且载流子浓度提升,使得材料的导电性得到提高;替换掺杂使得6H-SiC在光学性质方面有所变化,介电函数实部和虚部在低能级处增大,吸收光谱从未掺杂的3.2 eV开始吸收变为略高于0 eV就开始;反射谱与电导率曲线发生红移等有益结果.

A plane-wave pseudopoten tial method(PBE)for generalized grodient approximation(GGA)of first principles density functional theory(DFT)is adopted to calculate the electronic structures and optical characteristics of the intrinsic and Co(replacing Si)doped 6 H-SiC systems.It is shown that Co doping will change 6 H-SiC from indirect band gap semiconductor with band gap of 2.016 eV to p-type semiconductor with band gap of 0.071 eV and lead it to be magnetic.The impurity energy levels in the band structure after doping is caused by the 3 d energy levels of Co;the carrier concentration which improves the electrical conductivity of the material.Replacement doping makes a change in 6 H-SiC optical properties,the real and imaginary parts of the dielectric function increase at low energy levels,and the absorption spectrum changes from 3.2 eV to slightly more than 0 eV.The reflection spectrum and electrical conductivity curve are red-shifted.The conductivity of 6 H-SiC is enhanced by doping,making its application in infrared light more extensively.