Nano Research

Article Title

Distance dependence of atomic-resolution near-field imaging on α-Al2O3 (0001) surface with respect to surface photovoltage of silicon probe tip


near-field scanning optical microscopy, near field, surface photovoltage, α-Al2O3 (0001), force detection


ABSTRACT Recently, we achieved atomic-resolution optical imaging with near-field scanning optical microscopy using photon-induced force detection. In this technique, the surface photovoltage of the silicon-tip apex induced by the optical near field on the surface is measured as the electrostatic force. We demonstrated atomicresolution imaging of the near field on the α-Al2O3 (0001) surface of a prism. We investigated the spatial distribution of the near field by scanning at different tip-sample distances and found that the atomic corrugation of the near-field signal was observed at greater distances than that of the atomic force microscopy signal. As the tip-sample distance increased, the normalized signal-to-noise ratio of the near field is in a gradual decline almost twice that of the frequency shift (Δf).

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Tsinghua University Press