Origin of the Band Gap Reduction of In-Doped β-Ga2O3

The structural and electronic properties of In-doped β-Ga₂O₃ are calculated by the GGA + U method based on density functional theory. 76 possible structural configurations of In-doped β-Ga₂O₃ with different In content are considered. The In atom prefers to replace the octahedral Ga atom and form the most stable structure of β-In_2xGa_2(1−x)O₃. The band gap of β-In_2xGa_2(1−x)O₃ is reduced linearly with the increase of In content x, which is related to the rising valence-band maximum (VBM) and the falling conduction-band minimum (CBM). An anatomical method on band gap variation is presented, and the volume deformation playing a key role on band gap reduction of β-In_2xGa_2(1−x)O₃. Charge exchange and structural relaxation act as stabilizers on band gap reduction to reduce the internal strain and improve the stability of β-In_2xGa_2(1−x)O₃.