Investigation of electronic structure, photoelectric and thermodynamic properties of Mg-doped β-Ga2O3 using first-principles calculation

Abstract

The influence of Mg doping concentration on the electronic structure, photoelectric and thermodynamic properties of Mg-doped β-Ga₂O₃ was systematically investigated using the GGA+U method based on density functional theory. The results show that Mg atoms preferentially substitute the Ga(2) atoms at octahedral sites, which is further supported by formation energy analysis. As the Mg doping concentration increases, both the lattice constants and volume show an increasing trend, while the β angle decreases. Mg doping introduces new impurity levels into the energy bands, leading to an increment of forbidden band-gap, and a 100 % spin polarization state appearing near the Fermi level. The covalent bond formed between Mg and O atoms displays strong ionic characteristics along with relatively weak bonding strength. Moreover, Mg doping causes a blue shift in the absorption edge together with the imaginary part of the dielectric constant. The heat capacity of β-Ga₂O₃ is enhanced with Mg doping, with Mg_0.06Ga_1.94O₃ demonstrating optimal heat capacity characteristics. With the increase of Mg doping concentration, the free energy decline rate gradually increases, indicating an enhancement in the thermodynamic stability of β-Ga₂O₃. These findings provide valuable insights and deepen the understanding of Mg doping effects in β-Ga₂O₃.