Researchers of the NanoElectronics Group at the MESA+ Institute for Nanotechnology in collaboration with the Paul Drude Institute in Berlin have developed a low-cost and easy approach to generate ultrahigh-frequency (up to 23 gigahertz) surface acoustic waves (SAWs) in silicon substrates. These waves have a very similar nature as the waves occurring in earthquakes. Fortunately, the waves generated in Twente have an amplitude smaller than a nanometer, this is a millionth of a millimeter. However, the effect of such an acoustic wave at the nanoscale is really huge. For example, electrons inside silicon can be captured and transported by these waves. This ‘conveyor belt’ mechanism is extremely useful for applications, such as the definition of a universal current standard, single photon sources, spintronic devices, and quantum information technology.
The results of the Twente group represent the highest surface acoustic wave frequencies ever realized in a silicon based system, and therefore can be considered a breakthrough. The present demonstration should open up the way for high-speed acoustically driven carrier control in silicon, by far the most important material in electronics. The results have been published in the American journal Applied Physics Letters.
(a) Electrical generation of SAWs by an interdigital transducer (IDT). (b) Layer sequence of devices. (c) Scanning electron microscope image of 80 nm IDT finger electrodes.
Ultrahigh-frequency surface acoustic wave generation for acoustic charge transport in silicon
S. Büyükköse, B. Vratzov, J. van der Veen, P. V. Santos, and W. G. van der Wiel, Appl. Phys. Lett. 102, 013112 (2013)
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