A statistical study on the origin of the polarization-dependent leakage in ferroelectric aluminum scandium nitride films

Abstract

The recently discovered wurtzite ferroelectrics (FEs) have been at the center of electronic materials research because of their process compatibility and remarkably high Curie temperatures (above 1100 °C), qualities required for high-temperature nonvolatile memory. Among the wurtzite FEs, aluminum scandium nitride (AlScN) is one of the most studied, and although significant progress has been made toward its implementation, questions remain regarding its high and polarization-dependent leakage current. In this manuscript, we discuss the origin of this polarization-dependent leakage in sputter-deposited AlScN FE films by analyzing temperature-dependent current–voltage (I–V) characteristics of metal-FE-metal devices. The results suggest that the difference in current density with polarization is due to bulk properties more than the electrode–FE interface. Further statistical analysis showed that if the Poole–Frenkel conduction model is used, this current density difference can be attributed to changes in the electron mobility and/or carrier (or trap) density with polarization and not due to changes in the trap depth.