Ultra-small oscillation amplitude nc-AFM/STM imaging, force and dissipation spectroscopy of Si(100)(2x1)

Abstract

Si(100)(2 x 1) surface is imaged using a new nc-AFM (non-contact atomic force microscopy)/STM with sub-Angstrom oscillation amplitudes using stiff hand-made tungsten levers. Simultaneous force gradient and scanning tunneling microscopy images of individual dimers and atomic scale defects are obtained. We measured force-distance and dissipation-distance curves with different tips. Some of the tips show long-range force interactions, whereas some others resolve short-range interatomic force interactions. We observed that the tips showing short-range force interaction give atomic resolution in force gradient scans. This result suggests that short-range force interactions are responsible for atomic resolution in nc-AFM. We also observed an increase in the dissipation as the tip is approached closer to the surface, followed by an unexpected decrease as we pass the inflection point in the energy-distance curve. (C) 2002 Elsevier Science Ltd. All rights reserved.