Doping induced indirect-to-direct bandgap transition of two-dimensional Ga2O3

Abstract

The doping effects on the electronic states of two-dimensional Ga2O3 are investigated by first-principle calculations. Substitutional Si, Ge or Sn atom at Ga sites results in donor doping behavior, while Mg, Ca or Sr dopant results in acceptor doping behavior. Particularly, the indirect bandgap of intrinsic monolayer Ga2O3 can be transformed into direct bandgap by doping these atoms. Charge density and PDOS results reveal that the interaction between the substitutional atom and neighboring O atoms affects the state distribution of the highest valence level and then the location of VBM is shifted. The indirect-to-direct bandgap transition also occurs for doped bilayer Ga2O3. However, doped bulk Ga2O3 always maintain indirect bandgap because of the lack of surface effects. The results are helpful to the development of two-dimensional Ga2O3 based photoemissive devices such as LED and lasers.