Dry surface cleaning of twisted bilayer graphene and angle dependent oxydation by UV irradiation.

Since production of single layer graphene (SLG) by mechenical exfoliation, it has been focal to many researches thanks to its extraordinary electrical conductivity and surface to volume ratio. these characteristics of graphene have benefit for apply gas sensor devices. Recently, twisted bilayer graphene (tBLG) attracted much attention of its extra ordinary physical properties, especially for its twist angle opto-electircal dependant characteristic. specifically, the magic angle (~1.1°) which shows super conducting characteristics. Moreover, tBLG shows higher mobility and conductivity than SLG. However, stacking two layers of sigle crystaline SLG has been reported to show side effect of introducing interlayer impurities during transfer process. Furthermore, Impurities of graphene surface, such as PMMA residues, degrade electrical conductivity and mobility. Here we report a CVD synthesis of clean interlayer tBLG to containing various twist angles. Top layer of tBLG was cleaned and oxidized by angle dependency under UV irradiation at ambient condition and characterized by Raman and electrical properties. We suggest that UV cleaning is the most effective method for surface cleaning of graphene. Also, we expect a correlation between oxidation rate and twist angle.