0.25-$\mu\hbox{m}$ GaN TeraFETs Optimized as THz Power Detectors and Intensity-Gradient Sensors

This letter reports on the influence of illumination conditions on the detector response of three-terminal devices. Antenna-coupled field-effect transistors for the plasmonic detection of THz radiation (TeraFETs) were realized using a 0.25- μm AlGaN/GaN process. Integrated bow-tie antennas are connected to the source, drain and gate terminals of electrically identical transistors in various ways. If radiation power is coupled symmetrically to the source and drain sides of the transistors' channels, TeraFETs become sensitive to gradient-intensity of the illumination power. It is found that fully asymmetric coupling, nontrivial to ensure at THz-frequencies, is required for a pure response to incident power.