Applied Physics

Mass-Producing SET Sensors

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Science  28 Apr 2006:
Vol. 312, Issue 5773, pp. 500
DOI: 10.1126/science.312.5773.500d

Weak electric fields at surfaces, whether in a solid-state device or a frozen cell section, can be mapped out noninvasively by mounting a single-electron transistor (SET) onto a scanning probe platform. However, the designs recently used to implement these scanning SETs have several drawbacks. Because the devices are easily damaged, elaborate methods for producing them one at a time are inefficient; moreover, the need for extremely low-temperature (<1 K) operating conditions, as well as laser-based feedback, limits the range of samples amenable to study.

Brenning et al. have fabricated SETs on the ends of silicon nitride cantilevers, which in turn are mounted on rigid quartz crystal resonators. These noncontact atomic force microscopy tips use the change in resonant frequency as the feedback signal and scan at heights of a few nanometers. More than 200 tip assemblies can be fabricated at a time via electron-beam lithography, and they have large enough charging energies to operate at pumped liquid helium temperatures. The authors demonstrate the device by scanning a SiO2 surface at 4.2 K. — PDS

Nano Lett. 6, 10.1021/nl052526t (2006).

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