Influence of Al₂O₃ crystallization on band offsets at interfaces with Si and TiNx

Experiments on internal photoemission of electrons from Si and TiNx into thin Al2O3 layers suggest that crystallization of amorphous Al2O3 to the cubic γ-Al2O3 is accompanied by only a ≈ 0.5 eV upshift of the conduction band bottom edge. As it is known that in transforming from the amorphous to the γ-phase, the bandgap of Al2O3 increases from 6.2 eV to 8.7 eV, more than 80% of this gap widening must occur at the VB side of the gap. The latter suggests that interaction between electron states of O anions plays the dominant role in the oxide gap widening.