Tuning the Semiconducting Properties in Co₃O₄/PMN–PT Heterostructures by Oxygen Vacancies and Domain Structure

Abstract

Epitaxial Co3O4 films with various oxygen vacancy densities were deposited on the (001)-, (011)-, and (111)-0.7Pb­(Mg1/3Nb2/3)–0.3PbTiO3 (PMN–PT) substrates to modulate the electrical properties. Experiment and calculation results demonstrate that the oxygen vacancies can reduce the resistivity of Co3O4 films. Meanwhile, the resistivity of Co3O4 films decreases in the order of (111) > (011) > (001) due to the various ferroelectric domain densities of PMN–PT substrates. The Co3O4/PMN–PT (001) heterostructure exhibits the lowest resistivity of 1.7 Ω cm at room temperature under the influence of oxygen vacancies and the ferroelectric domain. The maximum relative resistance variation of Co3O4 films reaches 200% under an external electric field as the result of the ferroelectric-field effect and the migration of oxygen vacancies. This work provides a powerful way to modulate the electrical properties of Co3O4 films and further broadens the application of Co3O4.