Dielectric enhancement with low dielectric loss in textured ZnO films inserted with NiFe

Abstract

The dielectric properties of textured ZnO/NiFe/ZnO heterostructured films have been demonstrated by applying a bimetallic NiFe inserted layer into ZnO films. High quality crystalline ZnO(002) textured films were deposited and displayed a dielectric constant value of around 12, confirmed at room temperature. Dielectric property measurements at 15 MHz and room temperature reveal that the as-deposited ZnO/NiFe/ZnO heterostructures with a 10 nm NiFe inserted layer have outstanding dielectric properties with large tunability of 67% and extra low dielectric loss of only 0.032. When compared with that of pure ZnO films or traditionally doped ZnO films, a single NiFe layer inserted into ZnO films can significantly improve the dielectric properties of the as-deposited heterostructures without any post-treatment. This phenomenon can be attributed to the redistribution of the strong interface charges found between the ZnO and NiFe layers combined with the stress effect and the space-charge or interfacial polarization generated between the insulator and the metallic regions segregated intrinsically in the heterostructures. Moreover, external magnetic field induced magneto-dielectric variation could be clearly observed, and the ZnO film inserted with an NiFe layer demonstrated an effective dielectric tunability. This research demonstrates that the dielectric and magnetic characteristics of the ZnO/NiFe/ZnO heterostructures can be effectively controlled by the bimetallic NiFe thickness and external magnetic field, which can provide valuable multifunctional behavior for potential novel applications in magneto-dielectric actuator/sensor devices.