Analysis of scanning probe used for simultaneous measurement of tunneling current and surface potential

The scanning probe microscope used for the simultaneous measurement of tunn eling current and surface potential (TSM) is analyzed. Using an electric im age method, the capacitance formed between the vibrating tip and plane samp le is calculated, assuming that the vibrating tip is a sphere electrode wit h a radius r. The formula expressing the displacement current and the capac itance is obtained. The resolution of the TSM is discussed, and concluded t hat the lateral resolution of the displacement current mode is better than one fifth of the tip radius r, e.g., about 1 mu m for r = 5 mu m. Finally, the distance between the tip and plane sample, and the tip radius were expe rimentally determined by comparing the theoretical relationship between the displacement current and the distance. (C) 1999 American Institute of Phys ics. [S0021-8979(99)03124-2].