Dielectric and Electro-Mechanical Properties Controlled by Polarization Switching in PbZr_0.2Ti_0.8O₃-ZnO Thin-Film Heterostructure

Development and characterization of new heterostructure materials and interfaces is critical for a sustained progress of the performance and functionality of electronic, electro-mechanical, and electro-optical devices. We report experimental studies of ferroelectric-semiconductor PbZr_0.2Ti_0.8O₃-ZnO heterostructure that enables ferroelectric polarization control of ZnO electronic and dielectric properties. The time-resolved x-ray microdiffraction measurements have revealed the piezoelectric coefficient d₃₃ of about 2.8 pm/V for pure high-quality epitaxial ZnO thin films. This linear piezoelectric response becomes more complex in the ferroelectric-ZnO heterostructure revealing different regimes of the electro-mechanical response. Polarization switching of PbZr_0.2Ti_0.8O₃ controls the interface electronic properties leading to switchable capacitance of at least 35% and over an order of magnitude difference in the interface charge carrier densities for two different polarization states of the ferroelectric layer. These results are important for understanding ferroelectric-semiconductor interactions and engineering new ZnO-based ferroelectric-semiconductor heterostructures such as BiFeO₃-ZnO or HfO₂-ZnO with new switchable electronic and dielectric properties.