Electric Nanoscale Device Sees Through Walls

École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland

Researchers have developed a nanodevice that operates more than 10 times faster than today’s fastest transistors and about 100 times faster than the transistors on most computers. The device generates high-power terahertz waves, which are notoriously difficult to produce and are useful in a variety of applications ranging from imaging and sensing to high-speed wireless communications.

Terahertz (THz) waves fall between microwave and infrared radiation in the electromagnetic spectrum, oscillating at frequencies of between 100 billion and 30 trillion cycles per second. These waves are prized for their distinctive properties: they can penetrate paper, clothing, wood, and walls as well as detect air pollution. Terahertz waves are a type of nonionizing radiation, meaning they pose no risk to human health. The technology is already used in some airports to scan passengers and detect dangerous objects and substances.

The nanodevice generates extremely high-power signals in a few picoseconds (one trillionth of a second), producing high-power THz waves. The technology, which can be mounted on a chip or a flexible medium, could one day be installed in smartphones and other handheld devices.

The compact, inexpensive, fully electric nanodevice works by producing a powerful “spark,” with the voltage spiking from 10 V (or lower) to 100 V in the range of a picosecond. The device is capable of generating this spark almost continuously, meaning it can emit up to 50 million signals every second. When hooked up to antennas, the system can produce and radiate high-power THz waves.

The device consists of two metal plates situated very close together, down to 20 nanometers apart. When a voltage is applied, electrons surge towards one of the plates, where they form a nano-plasma. Once the voltage reaches a certain threshold, the electrons are emitted almost instantly to the second plate. This rapid movement enabled by such fast switches creates a high-intensity pulse that produces high-frequency waves.

Conventional electronic devices are only capable of switching at speeds of up to 1 V per picosecond — too slow to produce high-power THz waves. The new nanodevice, which can be more than 10 times faster, can generate both high-energy and high-frequency pulses. The device can be integrated with other electronic devices such as a transistor.

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