Epitaxy and bonding of peelable ZnO film on graphene/ZnO substrate

High-quality flexible ZnO films are commonly used to prepare ZnO-based flexible devices. However, the existing methods for preparing flexible films have some bottlenecks, such as poor quality, high cost, and complex steps in the flexible production process. The present study presents results on peelable ZnO film grown on graphene/ZnO substrate by plasma-assisted molecular beam epitaxy (PAMBE). Double-layer graphene (DLG) can be used as a release layer to convert the contact between ZnO film and substrate from chemical bonding to van der Waals force interactions. Hence, the ZnO film grown on graphene/ZnO substrate can be peeled off by a thermal release tape. The O-plasma irradiation introduced many dangling bonds on the surface of graphene. These dangling bonds combined with Zn atoms to form COZn bonds in the nucleation of the ZnO film. This study proposes a bonding mechanism of ZnO on graphene, verified by experiments. The flexible ZnO film obtained by this method provides a simple and feasible way for potential applications in ZnO-based flexible optoelectronic devices.