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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%.

We have investigated the influence of island size on the operation of single electron tunneling (SET) devices. The self-heating, self-capacitance, and charge noise have been determined for six SET transistors with island sizes varying from 0.17×0.17 μm2 to 5×5 μm2. The I–V characteristics of these devices can be well fit to a model where the heat flow from the device is limited by the electron-phonon coupling. The best fit to this model was obtained with an electron-phonon coupling parameter of Σ=0.3×109 W K−5 m−3. We have found a clear indication that the charge noise of our SET transistors, which are fabricated with the usual techniques, increases with increasing island size. These results have been used to estimate the thermal error of a single electron turnstile assuming that self-heating and charge noise in the turnstile are the same as in our SET transistors. The accuracy of the turnstile is dramatically reduced by the self-heating and the charge noise.

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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