Fig. 4: The mechanism for transferring high-intactness and clean suspended graphene membrane with CD as support layer.

a Optical image of the as-transferred graphene on TEM holey lacey grid with the assistance of CD after completely etching Cu substrate, we can acquire the sublimation way of CD from the images at different time stages. The rightest picture is the SEM image of the final obtained single-layer suspended graphene and the intactness is quite high. b The dry process of suspended water membrane on TEM SiN holey substrate, it is observed that continuous water membrane can support graphene while fractured water membrane cannot do that and the water membrane can be broken within several seconds. c Illustration of dry process in traditional transfer without CD, and single-layer suspended graphene with size larger than 5 μm can be easily broken. \({\gamma }_{{\rm{s}}-{\rm{l}}}\) is the interfacial tension between graphene and liquid. d Illustration of sublimation of CD in our transfer way with CD as the support layer, and single-layer suspended graphene films with quite large size can be obtained. \({\gamma }_{{\rm{s}}-{\rm{s}}}\) is the interfacial tension between graphene and CD.