Science 329, 1316–1318 (2010)

Electronic devices made of conventional semiconductors such as silicon are unable to operate at high temperatures because they experience leakage currents — that flow in the off state — and other problems at the temperatures encountered in applications such as advanced propulsion systems and deep-well drilling. Silicon carbide (SiC) has much better thermal properties than silicon, but field-effect transistors made from this material tend to be slow and relatively bulky. Now Te-Hao Lee and co-workers at Case Western Reserve University in the USA have made an electromechanical switch from SiC that can operate at a frequency of 500 kHz at 500 °C.

The device made by Lee and co-workers contains two identical three-terminal switches in a simple circuit. The source in each switch is a cantilever that can be brought into contact with the drain by applying a voltage to the gate. The new switch is about three orders of magnitude smaller than a SiC field-effect transistor, and has a leakage current of less than ten femtoamps, which represents an improvement of four orders of magnitude.

The Case Western team was able to operate the SiC switches for more than 21 billion cycles at 25 °C and for more than 2 billions cycles at 500 °C, although the reasons for failure at the higher temperature are not yet understood.