Volume-matched ferroelectric and piezoelectric ZnO/MgO superlattice

Abstract Wurtzite ZnO as a multifunctional material is attractive due to the ferroelectricity and piezoelectricity; Cubic MgO is also a very useful insulator oxide for applications in emerging electronics. Using the volume matching condition, we construct a stable 1 × 1 ZnMgO superlattice alternating along the crystallographic c-direction. We then calculate the electronic, ferroelectric and piezoelectric properties of the ZnMgO superlattice through density-functional theory. It is found that the epitaxial tensile strain can effectively reduce the polarization barrier without significantly reducing the polarization, increase the piezoelectric constant e33 and soften the elastic constant C33. In addition, the piezoelectric modulus d33 is enhanced by about 4 times, and the electromechanical coupling coefficient k33 is nearly doubled at 4% strain.