First principles modeling of defects in the Al2O3/In0.53Ga0.47As system

Abstract

Density functional theory paired with a first order many-body perturbation theory correction is applied to determine formation energies and charge transition energies for point defects in bulk In0.53Ga0.47As and for models of the In0.53Ga0.47As surface saturated with a monolayer of Al2O3. The results are consistent with previous computational studies that AsGa antisites are candidates for defects observed in capacitance voltage measurements on metal-oxide-semiconductor capacitors, as the AsGa antisite introduces energy states near the valence band maximum and near the middle of the energy bandgap. However, substantial broadening in the distribution of the GaAs charge transition levels due to the variation in the local chemical environment resulting from alloying on the cation (In/Ga) sublattice is found, whereas this effect is absent for AsGa antisites. Also, charge transition energy levels are found to vary based on proximity to the semiconductor/oxide interfacial layer. The combined effects of alloy- and proximity-shift on the GaAs antisite charge transition energies are consistent with the distribution of interface defect levels between the valence band edge and midgap as extracted from electrical characterization data. Hence, kinetic growth conditions leading to a high density of either GaAs or AsGa antisites near the In0.53Ga0.47As/Al2O3 interface are both consistent with defect energy levels at or below midgap.