Ferroelectric Properties and Structural Characteristics of Mn and Zr Co-Substituted ZnO Thin Films

Wurtzite-type ferroelectrics have garnered significant attention as next-generation memory materials due to their high remanent polarization and excellent scalability.However, reported ZnO-based ferroelectrics exhibit high coercive fields close to their dielectric breakdown voltage, resulting in poor insulation reliability.In this study, we investigated the effects of Mn and Zr co-substitution into Zn sites to identify new dopants capable of inducing observable ferroelectricity in ZnO.Thin films with compositions of Zn 1-x (Mn, Zr) x O (x = 0-0.20)were fabricated using pulsed laser deposition.X-ray diffraction analysis confirmed that both the c-axis length and the c/a ratio increased with the substitution concentration.Furthermore, polarization-electric field measurements successfully revealed distinct ferroelectric hysteresis loops for the compositions at x = 0.10 and x = 0.15.Although conventional ZnO-based ferroelectrics were reported to show the ferroelectricity by decrease of the c/a ratio, Zr and Mn co-substitution was revealed to induce ferroelectricity with an increase of the c/a ratio.