First-principles study on the effects of the intrinsic defects in GaAs saturable absorber

First-principles calculations are performed for the effects of the intrinsic defects in GaAs saturable absorber, using the state-of-the-art computational method with the Heyd-Scuseria-Ernzerhof (HSE) hybrid functional to correct the band gap. The defect energy levels corresponding to all point defects and their electrical characteristics are analyzed from the aspects of density of states and band structures. Furthermore, the partial band decomposed charge density of the defect bands are also been studied. The relationships between defect energy levels and EL2 deep-level defect will be helpful in ascertaining the origin of the EL2 deep-level defect in GaAs.