Influence of laser irradiation on local electronic properties of graphene in the presence of water adsorbate

The effect of volatility of local electronic properties in multilayered (3-6 layers) graphene irradiated by nanosecond laser pulses with a wavelength 532 nm in humid atmosphere was found. The experiments were carried out in situ in a scanning probe microscope (SPM) with Pt/Si tip. It was established that along with local profile transformation of graphene sheet (the formation of "nanocrater" with depth up to 2 nm and ~1 µm diameter) in the zone of the laser action (~0,5 µm) a decrease (~20 meV) of the electrons work function was observed. It takes place in the region larger but comparable with the irradiation spot size. Analysis of the experimental data on local electrical conductivity have shown that the bottom of conduction band for graphene in laser irradiation area was reduced by ~ 50 meV. The observed changes of graphene physical properties were associated with the laser-induced radial displacement of the water layer intercalated between graphene and substrate. In addition, it was experimentally established that the graphene work function was decreased significantly less than can be expected for an "ideal" 3 - 6 layer graphene. The investigated process of laser-induced changes of graphene properties demonstrated the reproducible character and long-term stability. Possibility of laser fabrication of arrays in graphene with periodic modulation of electronic properties was demonstrated.