Figure 3: Characterization of defective graphene by AFM and nanoindentation.
From: Effect of defects on the intrinsic strength and stiffness of graphene
(a) AFM image of a graphene sheet fully covering a hole. High-resolution AFM images of suspended graphene sheet (b) before and (c) after oxygen plasma exposure of 55 s. It is obvious that the plasma treatment leaves the surface pock-marked with a multitude of nanopores that are several nm in size (the dark spots in the image represent the nanopores). (d) Typical force versus displacement curves of AFM nanoindentation test for defective graphene exposed to oxygen plasma for 30 s. Tests are repeated at increasing indentation depths until the sample breaks. The curves fall on top of each other (no hysteresis), which indicates no significant sliding or slippage between the graphene membrane and the substrate. The AFM images in the inset of d show a graphene sheet before and after fracture. Scale bars, 1 μm (a); 100 nm (b,c).
