A YBCO-based conductive material can be used as an electrode, which can contact a dielectric such as a high k dielectric. Alternatively, a material with a narrow conduction band can be used as an electrode, which can contact a dielectric such as a high k dielectric. By aligning the dielectric with the band gap of the YBCO-based electrode or with the band gap of the narrow-band conductive material electrode, e.g., the conduction band minimum of the dielectric falls into one of the band gaps of the YBCO-based or narrow-band conductive material, thermionic leakage through the dielectric can be reduced, since the excited electrons or holes in the electrode would need higher thermal excitation energy to overcome the band gap before passing through the dielectric layer.