First principles calculations of the electronic structure of GaAs in (001), (011) and (111) electric field directions

GaAs is an important short-wave near-infrared photocathode material. In this paper, the first-principles plane wave pseudopotential method based on the density functional theory framework is used to study the influence mechanism of external electric field on the electronic structure of GaAs. Applying an electric field in different directions to GaAs shows that the (011) electric field direction has the strongest effect on opening the GaAs energy gap. Then, the electric fields of different strength are applied along the (011) direction. The results show that the energy gap of GaAs is 0.937eV when no electric field is applied. With increasing the electric field strength in the (011) direction, the energy gap of GaAs decreases gradually, when the electric field strength reaches 1eV/A/e, the energy gap of GaAs is almost zero. Notice that in the conduction band region where the total density of state of GaAs gradually shifts to Fermi surface and the Span gradually decrease with increasing the electric field strength, while valence band is the opposite of the conduction band.