C-Mg掺杂GaN电子结构和光学性质的第一性原理研究

基于密度泛函理论第一性原理的方法,计算了GaN、C单掺、Mg单掺和C-Mg共掺体系的电子结构和光学性质,计算结果表明:掺杂后,GaN体系的晶格发生畸变,有利于光生空穴-电子对的分离,C-Mg共掺体系结构最稳定,掺杂体系的禁带宽度均减小,其中C-Mg共掺体系的禁带宽度最小,在禁带中引入了杂质能级,说明掺杂可有效降低电子跃迁所需的能量.在光学性质方面,掺杂后,GaN在低能区介电峰和吸收峰均发生红移,且静介电常数增大;其中C-Mg共掺体系的对可见光的吸收最强,极化能力最强,因此C-Mg共掺将有望提高GaN在光催化性能和极化能力.

First principle study on electronic structure and optical properties of C-Mg doped GaN

Based on the first principles of density functional theory, the electronic, structural and optical properties of GaN, C single-doped, Mg single-doped and C-Mg co-doped systems are calculated. The results show that: There are lattice distortions of GaN in these doped systems, it is advantageous for photogenic hole-electron pair separation The structure of C-Mg co-doped system is the most stable, and the band gap widths of these doped systems decrease, among them the band gap width of C-Mg co-doped system is the smallest; the impurity levels introduced in the forbidden band can effectively reduce the energy required for electron transition. In terms of optical properties, the dielectric peaks and absorption peaks of the doping GaN systems in the low energy region are red shifted, and the static dielectric constants increases. Among them, C-Mg co-doping system has the strongest absorption of visible light and polarization ability. Therefore, C-Mg co-doping is expected to improve the photocatalytic performance and polarization ability of GaN.