Effects of Dielectric Interlayer on Polarization Switching and Rectifying Characteristics in Al0.8Sc0.2N/HfO2 Ferroelectric Diodes

초록

Ferroelectric (FE) diodes configured in the metal-ferroelectric-metal (MIFM) structure are promising candidates for non-volatile memory. While recent studies emphasized bulk FE properties, interfacial characteristics have not been carefully considered. In this work, we investigate the HfO2/Al0.8Sc0.2N interface by examining its impact on switching and rectifying characteristics in MIFM FE diodes with variable HfO2 thicknesses (2/4/6 nm). Electrical characterization reveal that the increased HfO2 thickness raises the coercive field (E-C) due to enhanced electrostatic effects and progressive interfacial oxidation from Sc-N to Sc-O bonds. This resulting oxygen substitutional defect (O-N) which may contribute to domain-wall pinning and reduced rectifying efficiency. Cycling tests clarify operating regime-dependent phenomena, including O-N redistribution-induced wake-up and eventual breakdown. Moreover, enhanced retention is observed after pre-cycling, originating from the stabilization of the interfacial defects rather than bulk properties. These findings underscore that E-C and device reliability are likely influenced by interfacial engineering, which is critical for the reliable operation of AlScN-based FE diodes.

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