Novel Terahertz nanodevices and circuits

Terahertz (THz) technology has attracted rapidly increasing attention due to a very broad range of potential applications, e.g., medical imaging and homeland security. Perhaps more importantly, developing electronic devices capable of operating at THz frequencies will have great impact on future generation computation and communication. Despite enormous effort in recent years, THz field is still largely unexploited due to the bottleneck issue of the lack of compact, solid-state, room-temperature detectors and emitters. Here we overview our recent work on the THz operations of novel nano-diodes that can detect and emit THz waves at room temperature. Apart from the very high speed, these novel diodes also have characteristics such as zero threshold and quadratic rather than exponential current-voltage response, which are particularly important for applications including THz imaging and energy harvesting. These unique characteristics are possible because the planar nanodevices are based on completely new working principles from conventional diodes, i.e., the rectifying functionality does not rely on any pn junction or tunneling barrier. In our experiments, different antenna structures including spiral, dipole and bow-tie are fabricated to couple the nanodevices to free-space THz waves up to a few THz. Apart from THz imaging and communications, the possibility to extend the technology to mid-infrared frequencies for heat energy harvesting is very attractive because of the potentially high efficiency and low cost as compared with conventional thermoelectric devices.