Graphene Layer-Dependent Electromechanical Responses and Interfacial Transport in CGO Thin Films

Oxide-based electromechanical materials are widely used in sensors, actuators, and energy conversion devices. Their performance is governed by electric-field-induced lattice deformation, and electromechanical responses have traditionally been tailored through composition, crystal structure, and defect engineering. However, the influence of electronic boundary conditions at two-dimensional material/oxide interfaces remains largely unexplored. Here, Gd-doped CeO2 (CGO) thin films were deposited on controlled numbers of graphene layers to investigate graphene layer-dependent effects in electrostriction and electrical transport. Structural characterization confirmed the formation of polycrystalline CGO layers on graphene, whereas the electromechanical response exhibited a pronounced dependence on the number of graphene layers. In particular, the bilayer graphene structure exhibited the highest electrostriction coefficient and distinctive electrical transport characteristics. Raman spectroscopy revealed systematic changes in the graphene 2D band after CGO deposition, whereas electrical transport measurements demonstrated R2T and nonlinear current-voltage behavior. Furthermore, the bias-dependent device-level resistance modulation indicated that the electrical characteristics of the graphene/CGO interface evolved under an applied electric field. Taken together, these observations are consistent with the possibility that graphene-dependent interfacial electrical conditions contribute to the electromechanical response of the CGO film. These findings identify the number of graphene layers as an important parameter governing the nonlinear electromechanical and interfacial transport behavior of CGO/graphene heterostructures.