Instrumentation and operation of the STM

The STM consists of a head, vibration isolation and electronics. The head contains the probe tip and its positioner. Fine control of position is always by piezoelectric actuator. Several geometries are possible, but a common design is a piezoelectric tube where a voltage applied across the thickness of the tube wall causes the tube to extend along its axis [147]. The tip is mounted on the end of the tube, and the sample surface (x, y) is perpendicular to the tube axis z (Fig. 6.14A). One electrode is on the inside of the tube, and 

The electronics of the STM must have low-noise high voltage amplifiers to drive the tip motions, and a sensitive low-noise amplifier chain for the tunneling current. These analogue signals are converted from and to digital signals for computer control. In both the scanner systems described above, the scan is not exactly planar. 

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