The concept of THz detection based on excitation of plasma waves in two-dimensional electron gas in Si FETs is one of the most attractive ones, as it makes possible the development of the large-scale integrated devices based on a conventional microelectronic technology including on-chip antennas and readout devices integration. In this work we report on investigations of Terahertz detectors based on low-cost silicon technology field effect transistors. We show that detectors, consisting of a coupling antenna and a n-MOS field effect transistor as rectifying element, are efficient for THz detection and imaging. We demonstrate that in the atmospheric window around 300 GHz, these detectors can achieve a record noise equivalent power below 10 pW/Hz0.5 and a responsivity above 90 kV/W once integrated with on-chip amplifier. We show also that they can be used in a very wide frequency range: from ∼0.2 THz up to 1.1 THz. THz detection by Si FETs pave the way towards high sensitivity silicon technology based focal plane arrays for THz imaging

Abstract: We report on ultrahigh sensitive, broadband terahertz (THz) detectors based on asymmetric double-grating-gate (ADGG) high electron mobility transistors, demonstrating a record responsivity of 2.2 kV/W at 1 THz with a superior low noise equivalent power of 15 pW/v Hz using InGaAs/InAlAs/InP material systems. When THz radiation is absorbed strong THz photocurrent is first generated by the nonlinearity of the plasmon modes resonantly excited in undepleted portions of the 2D electron channel under the high-biased sub-grating of the A-DGG, then the THz photovoltaic response is read out at high-impedance parts of 2D channel under the other sub-grating biased at the level close to the threshold. Extraordinary enhancement by more than two orders of magnitude of the responsivity is verified with respect to that for a symmetric DGG structure.

We report on ultrahigh sensitive, broadband terahertz (THz) detectors based on asymmetric double-grating-gate (ADGG) high electron mobility transistors, demonstrating a record responsivity of 2.2 kV/W at 1 THz with a superior low noise equivalent power of 15 pW/v Hz using InGaAs/InAlAs/InP material systems. When THz radiation is absorbed strong THz photocurrent is first generated by the nonlinearity of the plasmon modes resonantly excited in undepleted portions of the 2D electron channel under the high-biased sub-grating of the A-DGG, then the THz photovoltaic response is read out at high-impedance parts of 2D channel under the other sub-grating biased at the level close to the threshold. Extraordinary enhancement by more than two orders of magnitude of the responsivity is verified with respect to that for a symmetric DGG structure

We have measured the Terahertz photoresponse of three types of FETs as a function of the temperature, to study the change of the dominant current mechanism. For all of them we have compared the photoresponse with its DC transfer characteristics, which is directly proportional to the conductivity.

We report on Terahertz wireless communications and fast imaging experiments at 300 GHz, using nanometer-sized transistors as detectors. The physical mechanism of the detection is related to the overdamped plasma waves in the transistor channel.

Development of new terahertz (THz) sensors is increasing in interest due to their potential for THz imaging and spectroscopy. One alternative to develop direct THz sensors is based in the oscillation of the plasma waves in the channel of sub-micron FETs.The n-channel Si/SiGe MODFETs used in this study were grown by MBE on a thick relaxed SiGe virtual substrate grown by low-energy PECVD on plain Si wafers.

Antenna-coupled field effect transistors have been developed as plasma-wave THz detectors in both InAs nanowire and graphene channel material. Room temperature operation has been achieved up to frequencies of 1.5 THz, with noise equivalent powers as low as a few 10-11 W/Hz1/2, and high-speed response.