▎ 摘　　要

We report the field emission characteristics of a few-layer pristine and N-doped graphene by the in-situ transmission electron microscopy. The measurements were performed with a Pt-Ir nanoprobe and at a vacuum gap of 400 nm. The turn on voltage, required to draw an emission current of 1 nA from pristine and N-doped graphene, was found to be 230 and 110 V, respectively. The lower turn on voltage for the N-doped graphene can be explained from the improved electrical conductivity and up-shift of the Fermi level with nitrogen doping. Structural deformation/contraction/buckling of the N-doped graphene sheet was observed with the field emission current exceeding similar to 6.9 mu A, which can be attributed to the Joule heating. (C) 2013 AIP Publishing LLC.