Direct transfer of graphene and application in low-voltage hybrid transistors†
A novel scotch tape assisted direct transfer of graphene onto different flexible and rigid substrates, including paper, polyethylene terephthalate, flat and curved glass, SiO2/Si, and a solution-processed high-k dielectric layer is presented. This facile graphene transfer process is driven by the difference in adhesion energy of graphene with respect to tape and a target substrate. In addition, the graphene films transferred by scotch tape are found to be cleaner, more continuous, less doped and higher-quality than those transferred by PMMA. Based on that, the tape transferred graphene is employed as a carrier transport layer in oxide thin-film transistors (TFTs) with different gate dielectrics (i.e., SiO2 and high-k ZrO2). The In2O3/graphene/SiO2 TFTs exhibit a high electron mobility of 404 cm2 V−1 s−1 and a high on/off current ratio of 105, while the counterpart In2O3/graphene/ZrO2 TFTs exhibit improved electron transport properties at an ultra-low operating voltage of 3 V, which is 20 times lower than that of SiO2-based devices. In contrast, the ZrO2-based TFTs with PMMA-transferred graphene exhibit no detective electrical properties. Therefore, the proposed scotch tape assisted transfer method will be particularly useful for the production of graphene films and other two-dimensional materials in more cost-effective and environmentally friendly modes for broad practical applications beyond graphene-based field-effect transistors (GFETs).