Fig. 1.

In situ TEM images showing a graphene sublimation pattern. (A) A TEM image showing a graphene sheet mounted on a TEM grid connected with an STM probe. (B) A HRTEM image of a 10-layer (5-bilayer) graphene. The graphene was Joule-heated to high temperatures by applying a bias voltage of ≈2.5 V. (C–E) Sequential HRTEM images showing the propagation of one void created by atom sublimation. The numbers 4 and 5 indicate the layer thickness being 4 and 5 bilayers, respectively. The arrowheads and SK, DK, and TK pointed out single, double, and triple atomic-plane-thick kinks on the BLEs, respectively. Arrows in D point out armchair edges. (F) A Fast Fourier Transformation of the graphene shown in C–E.