A reliable process has been developed for the fabrication of multilevel single-electron tunneling (SET) devices. Using this process, we have fabricated SET devices with Au-SiO-Al and Al-AlOx-SiO-Al overlap capacitors. The SET transistors exhibit voltage gain and, despite the complex device structure, have a low charge noise (7×10−5e/√Hz). Moreover, the use of overlap capacitors in SET devices results in a reduction of cross capacitances down to 8%.

A microfabricated electrontunneling accelerometer as a directional underwater acoustic sensor AIP Conf.A single-electron tunneling transistor has been directly coupled on-chip to a high electron mobility transistor. The high electron mobility transistor ͑HEMT͒ is used as an impedance matching circuit with a gain close to unity. The HEMT transformed the 1.4 M⍀ output impedance of the single electron tunneling ͑SET͒ transistor by two orders of magnitude down to 5 k⍀, increasing its bandwidth to 50 kHz. This circuit makes it possible to observe the motion of individual electrons at high frequencies. The requirements for the bandwidth in high frequency applications is discussed.

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