【摘要】 掺杂是改进半导体禁带宽度的常用手段，而单掺杂与共掺杂对提高体系光催化性能的程度各不相同，为了更清楚的了解哪种方法对光催化性能的影响更大，因此本文利用GGA+U超软赝势法对本征GaN、Cu单掺及Cu-X(X=Cl, S和O)共掺GaN体系的电子结构及光学性质进行了研究.结果表明：共掺体系更加稳定，且共掺体系中Ga—N键的共价性更强，说明杂质数量越多对体系的晶格畸变影响越大；杂质的引入使体系产生了杂质能级，从而减小了体系的禁带宽度，共掺体系中还出现了空穴富余的现象，这有利于电子-空穴对的分离，进而提高体系的光催化性能；与单掺相比，共掺体系的吸收光谱红移幅度更大，由此可以推测出共掺对改善体系光催化性能的效果更显著.更多还原

【Abstract】 As a new material, the two dimensional semiconductor photocatalyst has attracted the attention of researchers in the degradation of environmental pollutants. Among them, the wurtzite GaN semicon-ductor has great research significance in the field of photocatalysis because of its advantages of no pollu-tion, energy conservation, and high electron mobility, but it has the defects of large bandgap and easy electron hole recombination. Thus, the application of GaN in real life is limited. Doping is one of the common methods to improve the bandgap of semiconductors, but the effects of single doping and co-doping on improving the photocatalytic performance of the system are different. To better understand which doping has a greater impact on the photocatalytic performance, it is also expected to study more efficient photocatalyst materials and provide a theoretical basis for experimental preparation, we studied the electronic structure and optical properties of intrinsic GaN, Cu single doped, and Cu-X(Cl, S, O) co-doped GaN systems by GGA + U ultra-soft pseudopotential method. The results show that due to the difference of the radius of doped atoms and that of Ga and N atoms, different degrees of distortion occur in each doped system, moreover, the covalence of the Ga-N bond in the co-doped system is stronger. It shows that the more the number of impurities, the greater the influence on the lattice distortion of the system. Compared with intrinsic GaN, the introduction of impurities leads to impurity levels, which provide a bridge for the transition of electrons from the valence band to the conduction band. The doped system produces orbital hybridization near the Fermi level, which destroys the integrity of the crystal and reduces the bandgap of the system. Compared with the single-doped system, the co-doped are more stable, and there are electrons and holes surplus in the co-doped systems, which is conducive to the separation of electron-hole pairs and improving the photocatalytic performance of the system. Moreover, the redshift of the absorption spectrum of the co-doped systems is greater, and the photocatalytic activity of the system is improved more obviously. It can be inferred that the effect of co-doping on improving the photocatalytic performance of the system is more significant. In this study, the photocatalytic performance of the Cu-S co-doped GaN system is the best. It is hoped that this research result is used to provide some help to solve the problem of environmental pollution.更多还原