Scientists from Russia and Germany have created a graphene-based broadband detector of terahertz radiation. The device could have potential for applications in communication and next-generation information transmission systems, security and medical equipment.
(a) shows a top view of the device, with the sensitive region magnified in (b). The labels S, D, and TG denote the source, drain, and top gate. A side section of the detector is shown in (c). Image from MIPT
The new detector relies on the interference of plasma waves. Plasma waves in metals and semiconductors have recently attracted much attention from researchers around the world. Like the more familiar acoustic waves, the ones that occur in plasmas are essentially density waves, too, but they involve charge carriers: electrons and holes. Their local density variation gives rise to an electric field, which nudges other charge carriers as it propagates through the material. This is similar to how the pressure gradient of a sound wave impels the gas or liquid particles in an ever expanding region. However, plasma waves die down rapidly in conventional conductors.