By using arrays of nanowires with intentionally broken symmetry, we were able to detect microwaves up to 110 GHz at room temperature. This is, to the best of our knowledge, the highest speed that has been demonstrated in different types of novel electronic nanostructures to date. Our experiments showed a rather stable detection sensitivity over a broad frequency range from 100 MHz to 110 GHz. The novel working principle enabled the nanowires to detect microwaves efficiently without a dc bias. In principle, the need for only one high-resolution lithography step and the planar architecture allow an arbitrary number of nanowires to be made by folding a linear array as many times as required over a large area, for example, a whole wafer. Our experiment on 18 parallel nanowires showed a sensitivity of approximately 75 mV dc output/mW of nominal input power of the 110 GHz signal, even though only about 0.4% of the rf power was effectively applied to the structure because of an impedance mismatch. Because this array of nanowires operates simultaneously, low detection noise was achieved, allowing us to detect -25 dBm 110 GHz microwaves at zero bias with a standard setup.

A new type of nanometer scale nonlinear device, called self-switching device (SSD) is realized by tailoring the boundary of a narrow semiconductor channel to break its symmetry. An applied voltage V not only changes the potential profile along the channel direction, but also either widens or narrows the effective channel width depending on the sign of V. This results in a strongly nonlinear I-V characteristic, resembling that of a conventional diode. Because the structure resembles a diode-connected FET (gate and drain shorted), we have modeled the device as a sideways turned FET, so that the trench width t corresponds to insulator thickness t ox and conducting layer thickness Z (inside the semiconductor!) corresponds to channel width W .

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