Leakage current spectroscopy of epitaxial ferroelectric/semiconductor heterostructures and their memory effect

The current through 3-dimensionally-aligned epitaxial BaTiO3/perovskite-semiconductor heterostructures was measured down to fA by changing applied voltage and the ambient temperature. At low applied voltage, the leakage current through the BaTiO3/hole-conduction-type semiconductor was relaxation-dominated and symmetric with regard to bias polarity, while it exhibited an ohmic conduction in BaTiO3/electron-conduction-type semiconductor. The current exhibited reproducible memory effect at a high forward bias which was sufficiently low to preserve insulating property. Similar current-voltage characteristics were found using a nano-scale electrode. By regarding the BaTiO3 as a semiconductor, the transient process of the band bending at BaTiO3 surface explains the above observations. (C) 1998 Elsevier Science B.V. All rights reserved.