Effects of Stoichiometry and A-site Substitution on the Electrical Properties of Ferroelectric YMnO3

Abstract
We proposed the use of RMnO3 (R: rare-earth elements) for metal-ferroelectric-insulator-semiconductor field-effect transistor (MFIS-FET) type ferroelectric random access memories (Ferroelectric RAMs). To decrease the leakage current in this material, the effects of nonstoichiometry and A-site substitution were studied. Current-voltage characteristics revealed that the carriers in the RMnO3 originate in excess oxygen and show Frenkel-Poole-type emission. Significant grain growth was observed in the Mn-rich composition. In particular, Mn-rich YbMnO3 shows the lowest leakage current and the best frequency dependence of dielectric permittivity.