Charge transition levels of the As-As dimer defect at the InGaAs/Al2O3 interface are determined through density-functional calculations. At variance with the GaAs/Al2O3 interface where this defect gives rise to states within the band gap, its defect levels at the InGaAs/Al2O3 interface lie well above the conduction-band edge, irrespective of the composition of the first-neighbor shell surrounding the defect. These results rule out the As-As dimer as possible origin of band-gap states at InGaAs/Al2O3 interfaces. (C) 2013 Elsevier B.V. All rights reserved.