Transfer-Free Quasi-Suspended Graphene Grown on a Si Wafer

The direct growth of graphene affording wafer-scale uniformity on insulators is paramount to electronic and optoelectronic applications; however, it remains a challenge to date, because it entails an entirely different growth mode than that over metals. Herein, the metal-catalyst-free growth of quasi-suspended graphene on a Si wafer is demonstrated using an interface-decoupling chemical vapor deposition strategy. The employment of lower-than-conventional H₂ dosage and concurrent introduction of methanol during growth can effectively weaken the interaction between the synthesized graphene and the underlying substrate. The growth mode can be thus fine-tuned, producing a predominantly monolayer graphene film with wafer-level homogeneity. Graphene thus grown on a 4 inch Si wafer enables the transfer-free fabrication of high-performance graphene-based field-effect transistor arrays that exhibit almost no shift in the charge neutral point, indicating a quasi-suspended feature of the graphene. Moreover, a carrier mobility up to 15 000 cm² V^-1 s^-1 can be attained. This study is anticipated to offer meaningful insights into the synthesis of wafer-scale high-quality graphene on dielectrics for practical graphene devices.