Fabrication of suspended graphene field-effect transistors by the sandwich method

A novel fabrication technique that can be used for making a series of suspended graphene field-effect transistors on Si-substrate is discussed. The electrical properties of graphene channel can be significantly degraded by defects and chemical residues between graphene and substrate. To minimize electrical degradation, a method of physically suspending graphene from the substrate has been considered while maintaining its structural integrity. To address this problem, we employed a sandwich method to fabricate a suspended GFET, realizing 76% device fabrication yield that is higher than those realized by the other methods. Furthermore, the degradation of electrical properties due to external factors decreased. As our method has a mechanically stable structure, it can be imposed to make electrical devices with various two-dimensional (2D) materials. Our method can also be applied to the engineering of future devices in various applications because a large amount of electrically clean samples can be manufactured at once.