Simultaneous Scanning Force/Tunneling Microscopy Using a Quartz Cantilever with a Tungsten Tip

摘要

Simultaneous scanning force/tunneling microscopy measurements are carried out on the Si(111)-(7 × 7) surface using quartz cantilevers. The retrace scanning mode enables constant height imaging even under heavy drift conditions at room temperature. Relatively clean tungsten tips produce huge time-averaged tunneling currents () in the chemical bonding regime. In contrast, when the tip is contaminated with Si atoms due to tip-surface contacts, is suppressed or is barely detectable, while the force offers even better atomic contrast. This can explain the variety of magnitudes of obtained previously by some groups. The conversion formula between and instantaneous tunneling current is also verified, which is required for comparison of results with different cantilever oscillation amplitudes.