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The effects of transition metal (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) doping on the stability, electronic structure and optical properties of β-Ga2O3 have been studied using GGA and GGA + U. The results show that the U value can correct the strong interaction of the d-layer, causing orbital hybridization and affecting the position and number of impurity energy levels. It can move the conduction band to higher energy levels and weaken the role of Ga-3p in the valence band. The Ti-doped β-Ga2O3 is easily formed, followed by V, Cr, Sc, Fe, Mn, Co, Ni, Cu, and Zn doping. Some bands change regularly with the increase of atomic number. All systems become degraded semiconductors after doping. All doping will make the β-Ga2O3 red shift. Among them, the absorption intensity of Cu doping in the visible light range is significantly improved.

The influence of transition metals (Sc, Ti, V, Cr, and Mn) doping at different distances on the magnetism of CdS is studied by using generalized gradient approximation combined with Hubbard U in the VASP package. The results show that the doping systems are more stable, easy to form, and the wurtzite structure of CdS is not changed. It is found that the systems are antiferromagnetic (AFM) when nearest neighbor doping, which is attributed to the direct charge transfers between two impurity ions. The systems are ferromagnetic (FM) when the doping distance increases further, since the double exchange interactions are observed among the 3d orbital of the transition metal, the Cd-5s and the S-3p orbitals are at conduction band minimum. We also found that the total magnetic moment of each ferromagnetic system increases with the order of SC to Mn-doping, the spin polarizability of Cr-doping system is 100%. The estimated Curie temperature indicates that the Cr- and Mn-doped CdS in this paper can achieve room-temperature ferromagnetic characteristics, especially the Cr doping is the most prominent. And TM-doping does not destroy the semiconductor characteristics of the system. Therefore, the TM-doped CdS can be used as an ideal dilute magnetic semiconductor functional material.