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Relaxation in resistance switching (RS) has severely hindered the stability of memory devices based on oxide-thin-film/ferroelectric heterostructures. In this work, Zn doped SnO2 (ZTO) thin films were deposited on (111)-0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-0.3PT) substrates to investigate the effect of oxygen vacancies (OVs) on resistance relaxation. The polarization-dependent resistance relaxation is observed in ZTO/PMN-0.3PT heterostructures. The largest relative change in resistance up to 53.6% within 20 min is ascribed to OV diffusion. Local aggregation of positively charged OVs with the application of poling electric field would enhance the Coulomb repulsion and strain in distorted lattice, which could accelerate the OV back-diffusion. Partial positively charged OVs are neutralized in the positive polarization state with the application of +10 kV/cm poling voltage, which weakens the relaxation compared to the negative polarization state. Our work helps to understand the interrelation between OVs and polarization-dependent relaxation of RS properties. [ABSTRACT FROM AUTHOR]

The reversible resistance switching (RS) effect of the Al/TiOx/TiO2/Al heterostructure is investigated in this study. This RS was attributed to space-charge-limited conduction (SCLC) as controlled by localized traps in the TiOx layer. The preexisting SCLC theory was extended to describe the abrupt resistance transition. An analytical model was developed with consideration of the ratio of free and trapped carrier density, which was extracted from the experimental data to show exponentially distributed traps in energy. The proposed model can be applicable to RS phenomena induced by interface-type traps in other material system. [ABSTRACT FROM AUTHOR]