Optimization of β-Ga₂O₃ Device Performance through Rare Earth Doping: Analysis of Stability, Electronic Structure, and Optical Properties

β-Ga₂O₃ is a wide bandgap material with promising applications in high performance electronics. Dopants play a vital role in optimizing device performance. Here, we systematically discussed the stability, electronic structure, and optical properties of trivalent rare earth ion (RE) doped β-Ga₂O₃ using the general gradient approximation method and Hubbard term. The theoretical results show that the doping systems, β‑Ga₂O₃:RE (RE = La, Ce, Pr, Nd, Pm, Sm, and Eu), are all stable and easy to form. It is worth noting that the β-Ga₂O₃:RE system becomes more stable with the decrease of the radius of the doping ions. When RE are doped into β-Ga₂O₃, the band gap is reduced and spin asymmetry occurs. The Nd, Pm, Sm, and Eu doping introduces the spin-up impurity energy level, which consists mainly of RE-4f states orbitals. Simultaneously, RE-4f induces spin asymmetry, causing the system to develop some magnetism. It is interesting to note that as the atomic number increases, the energy levels of the impurities move sequentially towards the top of the valence band. The conductivity of the system increases after the rare earth is doped with β-Ga₂O₃. And the absorption spectra of β-Ga₂O₃ show a red shift, which indicates that the visible light absorption of β‑Ga₂O₃ is improved by doping with rare earth elements, especially Sm and Eu.