Relationship between optical dielectric constant and XPS relative chemical shift of 1s and 2p levels for dielectric compounds

We find a new relationship between the optical dielectric constant of Al dielectric films and their chemical shifts measured by X-ray photoelectron spectroscopy (XPS). We measure the difference between core-level binding energy shift for Al 1s and core-level binding energy shift for Al 2p, ΔE _1s - ΔE_2p, for AlN using high-resolution high-energy synchrotron radiation. We find that ΔE_1s - ΔE _2p correlates well with the optical dielectric constants of Al, AlN, and Al₂O₃. This is consistent with the case of our previously reported Si compounds. First-principles calculations are performed to determine the mechanism behind the observed correlation.