The structural properties and energy levels of simple intrinsic defects in gallium arsenide were investigated. The first-principles calculations involved boundary conditions which were appropriate for charge defects in super-cells and permitted quantitatively accurate predictions of defect charge transitions to be made using a super-cell approximation. The calculations were demonstrated to be convergent with respect to cell-size, and the sensitivity of the model to Ga pseudopotential construction (3d core or 3d valence) and density functionals (local density or generalized gradient approximation) was assessed. These precautions led to the first quantitatively reliable survey of defect levels in GaAs, and to a reassessment of the available data and the complexity of GaAs defect chemistry. The computed defect-level spectrum spanned the experimental GaAs band-gap, and the defects exhibited multiple bistabilities; with sometimes overlapping negative-U systems.

Simple Intrinsic Defects in Gallium Arsenide. P.A.Schultz, O.Anatole von Lilienfeld: Modelling and Simulation in Materials Science and Engineering, 2009, 17[8], 084007