Tuning the Electronic Structure of ZnO Bilayer: A First-Principles Study

: In this study, a ZnO bilayer is modeled, and the electronic structure is investigated by a first-principles calculation. Unlike a ZnO monolayer, the Zn and O atoms in the same layer of a ZnO bilayer have a small difference in the z coordinate, which is attributed to both intralayer and interlayer actions. An external electric field perpendicular to the basal plane causes a low-buckled structure of the bilayer, and the deformation increases with the E-field. The electronic structure of the ZnO bilayer can also be tuned by the E-field. Charge transfer increases between the upper and the lower layers, and the bilayer shows more metallicity when the E-field increases. The present study can help us understand more about the electronic structures of ZnO materials for potential applications in electronics and optoelectronics.