The waveform separation of displacement current and tunneling current using a scanning vibrating probe

A measuring system that separates the both waveforms of displacement and tu nneling current using a scanning vibrating probe is described. In the measu ring system, the displacement and tunneling current flow periodically in ac cordance with the perpendicular vibration of the probe. The external circui t current is measured by oscilloscope and is separated into both waveforms of the displacement and tunneling current by utilizing the phase difference of them. The waveform of the displacement current is also analyzed by assu ming the presence of excessive surface charges above the sample. Consequent ly, we can determine the mean distance between the probe and sample, and th e offset voltage which is built up by excessive surface charges and work fu nction difference of the probe and sample. (C) 2001 Elsevier Science B.V. A ll rights reserved.