Leakage current through epitaxial BaTiO3 films was investigated to cla
rify the difference between the characteristics of nanometer and milli
meter-size metal contacts. SrTiO3:Nb bottom electrode revealed genuine
properties of a single metal/BaTiO3 contact and demonstrated that bre
akdown voltage and leakage current density at both nanometer and milli
meter-size contacts were controlled by the Schottky barrier. However,
in marked contrast with millimeter-size contacts, nanometer-size conta
cts conducted little current below breakdown voltage and repeatedly ex
hibited abrupt breakdowns having a giant current density >10 A mm(-2).
The breakdown field was as high as 0.45 MV cm(-1) at the forward bias
, while no breakdown occurred up to 0.5 MV cm(-1) at the reverse bias.
(C) 1998 American Institute of Physics. [S0003-6951(98)00719-0].