Photoconductivity modulation behavior based on LiNbO₃/graphene heterostructure for ultraviolet detection

Surface acoustic wave (SAW) technology based on lithium niobate (LiNbO₃) piezoelectric crystals has emerged as a powerful tool for investigating the mechanism of acoustoelectric interactions, relatively few attempts have focused on acoustophotoelectric research. Graphene has attracted extensive attention in the field of optical research due to its unique properties such as extremely high carrier mobility and broadband tunability. The LiNbO₃/graphene coupling structure based on photoconductor-induced acoustic wave frequency shift is emerging as a novel approach to investigate the acoustophotoelectric response. In this study, we present a hybrid SAW-structure LiNbO₃/graphene. Ultraviolet (UV) light is used as an effective strategy to control charge carrier changes in graphene, while the dynamic process is detected using the SAW technology. Results show that the sensitivity of the LiNbO₃/graphene SAW device operating at 93 MHz is 4.09 ppm/(mW/cm²). Further, graphene was doped with HAuCl₄ solution to enhance its photoelectronic properties, the sensitivity reaches 7.24 ppm/(mW/cm²). The UV sensitivity of the doped LiNbO₃/graphene is 1.77 times higher than that of the undoped device. The incorporation of HAuCl₄ into graphene leads to multitude effects that collectively enhance photoelectric performance, including modified Fermi-Level, increased charge carrier density. This device structure and research methodology provide significant technical and theoretical support for the development of graphene-based photoelectronic devices based on SAW technology.