In Situ Local Band Engineering of Monolayer Graphene Using Triboelectric Plasma

Abstract Graphene, a promising material with excellent properties, suffers from a major limitation in electronics due to its zero bandgap. The gas molecules adsorption has proven to be an effective approach for band regulation, which usually requires a harsh environment. Here, O 2 − ions produced with triboelectric plasma are used for in situ regulation of graphene, and the switching ratio can reach 10 10 . The O 2 − ions physical adsorption will reduce the Fermi‐level ( E F ) of graphene. As the E F of graphene is lower than the lowest unoccupied molecular orbital (LUMO) level of O 2 −, the adsorption of O 2 − changes from uniform physical adsorption to local chemical adsorption, thereby realizing the semiconductor properties of graphene. The local graphene bandgap is calculated to be 83.4 meV by the variable‐temperature experiment. Furthermore, annealing treatment can restore to 1/10 of the initial conductance. The C─O bond formed by O 2 − adsorption has low bond energy and is easy to desorb, while the C═O bond formed by adsorption on defects and edges has higher bond energy and is difficult to desorb. The study proposes a simple in situ method to investigate the microscopic process of O 2 − adsorption on the graphene surface, demonstrating a new perspective for local energy band engineering of graphene.