We consider a terahertz detector based on a graphene ballistic rectifier integrated with an antenna. The device demonstrates an extrinsic responsivity of hundreds of V/W in the range 70-440 GHz at room temperature with no indications of a cut-off frequency up to 0.44 THz. The device also demonstrates linear response for more than 3 orders of magnitude of power input due to its zero threshold voltage and its high saturation current.

An overview of main results concerning THz detection related to plasma nonlinearities in nanometer field effect transistors is presented. In particular nonlinearity and dynamic range of these detectors are discussed. As the main result, we will show some of the first real-world applications of the FET THz detectors: demonstrators of the imager developed for fast postal security and industrial nondestructive quality control.

Recent advances in THz detection with the use of CMOS technology have shown that this option has the potential to be a leading method of producing low-cost THz sensors with integrated readout systems. This review paper, based on authors’ years of experience, presents strengths and weaknesses of this solution. The article gives examples of some hints, regarding radiation coupling and readout systems. It shows that silicon CMOS technology is well adapted to the production of inexpensive imaging systems for sub-THz frequencies. As an example paper presents the demonstrator of a multipixel Si-CMOS THz spectroscopic system allowing for chemical identification of lactose. The THz detectors embedded in this system were manufactured using the CMOS process.

A graphene ballistic rectifier is used in conjunction with an antenna to demonstrate a terahertz (THz) detector and imager. The device is used to take an image of an optically opaque object at 0.68 THz demonstrating potential in both medical and security imaging applications.

We present experimental studies of terahertz radiation detection by InP double heterojunction based transistors. We analyze the relation between their static characteristics and the experimentally determined voltage and current responsivities, showing importance of internal device parasitic capacitances and the external circuit loading effects. Finally, we demonstrate the use of these transistors for terahertz radiation computed tomography leading to 3D visualization of concealed objects. Our results pave the way towards wide use of heterojunction based transistors for terahertz imaging.

We report on temperature-dependent terahertz spectroscopy of a three-layer InAs/GaSb/InAs quantum well (QW) with inverted-band structure. The interband optical transitions, measured up to 16 T at different temperatures by Landau-level magnetospectroscopy, demonstrate the inverted-band structure of the QW. The terahertz photoluminescence at different temperatures allows us to directly extract the optical gap in the vicinity of the Γ point of the Brillouin zone. Our results experimentally demonstrate that the gap in the three-layer QWs is temperature independent and exceeds by four times the maximum band gap available in the inverted InAs/GaSb bilayers.