【International Papers】Point Defects in Silicon-Doped β-Ga₂O₃:Hybrid-DFT Calculations

      Researchers from the Institute of Plasma Physics and Laser Microfusion of Poland have published a dissertation titled " Point Defects in Silicon-Doped β-Ga₂O₃: Hybrid-DFT Calculations " in ACS Omega.

Abstract

      In this work, hybrid density functional theory calculations are used to evaluate the structural and electronic properties and formation energies of Si-doped β-Ga₂O₃. Overall, eight interstitial (Si_i) and two substitutional (Si_Ga) positions are considered. In general, our results indicate that the formation energy of such systems is significantly influenced by the charge state of the defect. It is confirmed that it is energetically more favorable for the substitution process to proceed under Ga-poor growth conditions than under Ga-rich growth conditions. Furthermore, it is confirmed that the formation of Si_GaI with a tetrahedral coordination geometry is more favorable than the formation of Si_GaII with an octahedral one. Out of all considered interstitial positions, due to the negative formation energy of the Si +3 charge state at i₈ and i₉ interstitial positions over the wide range of Fermi energy, this type of defect can be spontaneously stable. Finally, due to a local distortion caused by the presence of the interstitial atom as well as its charge state, these systems obtain a spin-polarized ground state with a noticeable magnetic moment.

Figure 1. Unit cell of the monoclinic phase of Ga₂O₃. Coordination environment of tetrahedral Ga_I and octahedral Ga_II positions (purple spheres are Ga atoms; gray spheres are O atoms).

Figure 2. Formation energies for Si impurity in β-Ga₂O₃ plotted against the Fermi energy for (A) Ga-rich and (B) Ga-poor conditions. The boundaries for the nonshaded region correspond to the VBM (E_F = 0 eV) and the CBM (E_F = E_g = 4.73 eV). Note that the calculations were performed on a large supercell with a dense k-point grid.

Paper Link：https://doi.org/10.1021/acsomega.3c05557