In Situ Local Band Engineering of Monolayer Graphene Using Triboelectric Plasma.

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.