Planar terahertz nanodevices

Terahertz (THz) technology has recently attracted much attention due to a very broad range of potential applications, such as security and medical imaging, radio astronomy, and ultra-fast electronics for future generation computation and communications. However, the THz field is still largely unexploited due to the bottleneck issue that is the lack of compact, solid-state, room-temperature emitters and detectors. In this paper, our work on novel THz electronic nanodevices is reviewed. This includes the recent experimental demonstration of room-temperature operation of a planar nano-diode at different THz frequencies, which is one of the first electronic nanodevices to work beyond 1 THz to date. Unlike conventional diodes, the nano-diode does not rely on pn junction or barrier structure. The new working principle enables a zero threshold and non-exponential current-voltage characteristic. Whereas the device is essentially a broadband THz detector, resonant features of localized surface plasma oscillations have been shown by Monte Carlo simulations to significantly enhance the electron dynamics at a few THz. We also show that similar planar nanodevices can generate Gunn-like oscillations in the THz range, and hence it is possible to fabricate THz detectors and emitters on the same chip. Very recent low-frequency noise measurements demonstrated advantages of the devices in terms of noise figures and particularly noise-equivalent power. Finally, our recent effort to combine the THz nano-diodes with nano-antennas for energy harvesting will be discussed.