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Introduction to Scanning Tunneling Microscopy
Abstract Scanning tunneling microscopy (STM) was invented by Binnig and Rohrer (see Fig. 2.1) [2,9]. Using the combination of a coarse approach and piezoelectric transducers, a sharp, metallic probing tip is brought into close proximity with the sample. The distance between tip and sample is only a few angstrom units, which means that the electron wave functions of tip and sample start to overlap. A bias voltage between tip and sample causes electrons to tunnel through the barrier. The tunneling current is in the range of pA to nA and is measured with a preamplifier.1 This signal is the input signal of the feedback loop, which is designed to keep the tunneling current constant during (x, y)-scanning. The output signal is amplified (high voltage amplifier) and connected to the z-piezo. According to the feedback output voltage and the sensitivity of the piezo (typically nm/V) the tunneling tip is moved backwards or forwards and the tunneling current is kept constant during acquisition of the image. This operation mode is called constant current mode.
Introduction to Scanning Tunneling Microscopy
Abstract Scanning tunneling microscopy (STM) was invented by Binnig and Rohrer (see Fig. 2.1) [2,9]. Using the combination of a coarse approach and piezoelectric transducers, a sharp, metallic probing tip is brought into close proximity with the sample. The distance between tip and sample is only a few angstrom units, which means that the electron wave functions of tip and sample start to overlap. A bias voltage between tip and sample causes electrons to tunnel through the barrier. The tunneling current is in the range of pA to nA and is measured with a preamplifier.1 This signal is the input signal of the feedback loop, which is designed to keep the tunneling current constant during (x, y)-scanning. The output signal is amplified (high voltage amplifier) and connected to the z-piezo. According to the feedback output voltage and the sensitivity of the piezo (typically nm/V) the tunneling tip is moved backwards or forwards and the tunneling current is kept constant during acquisition of the image. This operation mode is called constant current mode.
Introduction to Scanning Tunneling Microscopy
Professor Dr. Meyer, Ernst (author) / Professor Dr. Hug, Hans Josef (author) / Dr. Bennewitz, Roland (author)
2004-01-01
30 pages
Article/Chapter (Book)
Electronic Resource
English
Barrier Height , Scan Tunneling Microscopy , Tunneling Current , Scan Tunneling Microscopy Image , Scan Tunneling Spectroscopy Physics , Spectroscopy and Microscopy , Surfaces and Interfaces, Thin Films , Measurement Science and Instrumentation , Solid State Physics , Condensed Matter Physics , Nanotechnology
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