Nitrogen passivation at GaAs:Al2O3 interfaces

The effects of nitrogen passivation at interfaces between III–V semiconductors and high dielectric constant oxides are calculated using the GaAs:Al2O3 interface as a model. Nitrogen replaces As from interface sites. The N-N dimer is found to be unstable and breaks into N dangling bonds. The N dangling bond has states lying well below the bulk valence band edge, away from the band gap, due to the electronegativity of nitrogen. Thus nitrogen is an effective passivant because it removes the states of two candidate species away from the gap.