Electron energy band alignment at the NiO/SiO2 interface

Abstract

Study of the NiO/SiO2 interface band diagram using optical absorption, photoconductivity, and internal photoemission measurements reveals that deposited Ni oxides have a band gap of 3.2±0.1 eV, with the top of the valence band at 5.3±0.1 eV below the conduction band of SiO2 and showing no measurable sensitivity to the oxygen surplus in the layer up to 20%. Annealing in a reducing ambient (forming gas) at 400 °C results in narrowing of the band gap and an up shift in the occupied electron state edge by ≈1 eV, which is tentatively associated with partial reduction in the NiO layer.