Investigation of the electrostatic forces in scanning probe microscopy at low bias voltages

• Published in: Surface and interface analysis Vol. 33; no. 2; pp. 155 - 158
• Main Authors: Patil, Shivprasad, Dharmadhikari, C. V.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.02.2002; Wiley
• Subjects: AFM; EFM; Exact sciences and technology; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Physics; Scanning probe microscopes, components and techniques; scanning probe microscopy; STM; Atomic force microscopy; Gold; Scanning probe microscopy; Tip surface interactions; Tunnel junction; Experimental study; STM; Electrostatic force; Pyrographite
• ISSN: 0142-2421; 1096-9918
• DOI: 10.1002/sia.1180

The electrostatic force between a gold tip and an atomically flat highly oriented pyrolytic graphite substrate has been measured as a function of tip– sample separation distance for low bias voltages (<1 v). The experiments involve phase‐sensitive detection of the reflected laser beam off a stiff oscillating cantilever as it approaches the sample. The results are compared with the theoretical model in which the tip– sample geometry is described by confocal hyperboloids of revolution. The general behaviour of the force curve was found to be in agreement with theoretical expectations only for distances of >600 Å. The deviations at smaller distances probably could be due to extraneous material such as graphite nanoflakes or a conducting liquid column present between tip and sample. The results have direct bearing on understanding the interaction forces in scanning probe microscopy techniques in which tip– sample junctions are biased. Copyright © 2002 John Wiley & Sons, Ltd.