Effects of Si concentration on electronic structure and optical gap of Si-doped β-Ga2O3

The electronic structures and the optical gaps of Si-doped beta-Ga2O3 with different Si concentration are studied by the generalized gradient approximation combined Hubbard U (GGA + U) method based on the density functional theory. The doping formation energy reveals that Si-doped beta-Ga2O3 is mainly realized in the form of substitutional Si rather than interstitial Si, and tends to obtain effective doping under O-poor condition. As substitutional Si concentration increases, the optical gap of Si-doped beta-Ga2O3 increases while the bandgap narrows, which are mainly attributed to the Burstein-Moss effect and the many-body renormalization effect. The bandgap widening Delta E-BM and the bandgap narrowing Delta E-BGN of Si-doped beta-Ga2O3 as a function of Si carrier concentration can be described by Pisarkiewicz's model and Schmid's empirical expression, respectively.