Structural and Electronic Properties of ZnO Bilayer and Twist Bilayer: A First-Principles Study

By using the first principles calculations, we study the structural and electronic properties of zinc oxide (ZnO) bilayers. Initial ZnO bilayer has a planar structure, which is different from bulk ZnO. Another kind of twist ZnO bilayer is designed by rotating 60° on the basis of ZnO bilayer structure with a Zn/O atom as the axis. Both the bilayers have stable structure and high symmetry. As the interlayer distance increases, the interaction of the upper and the lower layers will weaken in both the bilayers. It is Zn atom but not O atom that plays a key role in the interlayer interaction, which has been confirmed by Mulliken charge and density of states results. The band gap of the bilayers can be tuned by translation motion, and ZnO twist bilayer shows a better performance than the initial bilayer in this study. Combining the two factors (interlayer distance and twist angle), ZnO bilayers are very hopeful to be utilized in 3D joints of nanoelectronic devices. Our results provide a detailed understanding of the structural and electronic properties of ZnO bilayers and help to predict the performance of ZnO-based two-dimensional nanoelectronics and nanocomposites.