Reduction-induced Fermi level pinning at the interfaces between Pb(Zr,Ti)O3 and Pt, Cu and Ag metal electrodes

The interface formation between Pb(Zr,Ti)O-3 and Pt, Cu and Ag was studied using in situ photoelectron spectroscopy. A strong interface reaction and a reduction of the substrate surface is observed for all three interfaces as evidenced by the appearance of metallic Pb species. Despite the different work function of the metals, nearly identical barrier heights are found with E-F - E-VB = 1.6 +/- 0.1 eV, 1.8 +/- 0.1 eV and 1.7 +/- 0.1 eV of the as-prepared interfaces with Pt, Cu and Ag, respectively. The barrier heights are characterized by a strong Fermi level pinning, which is attributed to an oxygen deficient interface induced by the chemical reduction of Pb(Zr,Ti)O-3 during metal deposition.