第一性原理研究In,N共掺杂SnO_2材料的光电性质

Material opto-electronic properties of In,N co-doped SnO_2 studied by first principles

采用全电势线性缀加平面波(FP-LAPW)的方法,基于密度泛函理论第一性原理结合广义梯度近似(GGA),运用Wien2k软件计算了In,N两种元素共掺杂SnO2材料的电子态密度和光学性质.研究表明,共掺杂结构在自旋向下和向上两方向上都出现细的局域能级,两者态密度分布不对称;带隙内自旋向下方向上产生局域能级,共掺化合物表现出半金属性;能带结构显示两种共掺杂化合物仍为直接禁带半导体,价带顶随着N浓度的增加发生向低能方向移动,带隙明显增宽;共掺下的介电函数虚部主介电峰只在8.58eV存在,且主峰位置发生右移,峰值强度显著增大;实部谱中,不同N浓度的两种共掺结构其静介电常数也明显增大,N的2p态与In的5s态之间发生强烈的相互作用;共掺下吸收谱中的吸收峰数目减少,吸收光波段范围增宽.

In this paper we use first-principles full potential linearized augmented plane wave method（FP-LAPW） to inwestigate density of states（DOS）,band structure and optical properties of the materials that doped with In and N.The results show that the doping structure has fine locat levels in both the spin-down direction and the spin-up direction and both state densities are symmetrical.The local levels are produced in the spin-down direction in the band gap,and co-doped compounds show being semi-metallic.The energy band structure indicates that the two co-doped compounds are still direct band gap semiconductors.The top of valence band shifts toward the low energy with the increase of the concentration of N,so obviously the band gap is widened.The main dielectric peak of imaginary part of dielectric function exists only at 8.58 eV,the position of main peak shifts to ward the right and the peak intensity increases significantly.The static dielectric constants of two different concentrations of N-doped structure also significantly increase,and a strong interaction takes place between the states of N 2p and In 5s.The number of peaks of co-doped absorption spectra reduces and the range of absorption wavelength is broadened.