Work function shifts, Schottky barrier height, and ionization potential determination of thin MgO films on Ag(001)

The electronic band structure and the work function of MgO thin films epitaxially grown on Ag(001) have been investigated using x-ray and ultraviolet photoelectron spectroscopy for various oxide thicknesses. The deposition of thin MgO films on Ag(001) induces a strong diminution in the metal work function. The p-type Schottky barrier height is constant at 3.85±0.10 eV above two MgO monolayers and the experimental value of the ionization potential is 7.15±0.15 eV. Our results are well consistent with the description of the Schottky barrier height in terms of the Schottky–Mott model corrected by an MgO-induced polarization effect.