采用基于第一性原理的局域密度近似方法研究了Al-N共掺SnO_2中不同N掺杂位置模型的电子结构和光学性质。掺杂Al或N元素后呈p型导电并且带隙拓宽,最大值可达到1. 748 e V; N元素引入了杂质能级,使得可见光区的介电函数虚部ε2(ω)增加,进而提高了低能区的吸收系数和吸收边发生了红移,反射率也增强。
The lattice, the band gap and the optical properties of n-type ZnO under uniaxial stress are investigated by first- principles calculations. The results show that the lattice constants change linearly with stress. Band gaps are broadened linearly as the uniaxial compressive stress increases. The change of band gap for n-type ZnO comes mainly from the contribution of stress in the c-axis direction, and the reason for band gap of n-type ZnO changing with stress is also explained. The calculated results of optical properties reveal that the imaginary part of the dielectric function decreases with the increase of uniaxial compressive stress at low energy. However, when the energy is higher than 4.0 eV, the imaginary part of the dielectric function increases with the increase of stress and a blueshift appears. There are two peaks in the absorption spectrum in an energy range of 4.0-13.0 eV. The stress coefficient of the band gap of n-type ZnO is larger than that of pure ZnO, which supplies the theoretical reference value for the modulation of the band gap of doped ZnO.
Yang PingLi PeiZhang Li-QiangWang Xiao-LiangWang HuanSong Xi-FuXie Fang-Wei
