We report on the photoresponse of 0.7-μm InP double heterojunction bipolar transistor to THz radiation of low and high intensities, when the collector is unbiased. At low intensities, the photoresponse is linear in radiation intensity. Under intense laser radiation, we observe a saturation at intensities > 15 kW/cm2, sample damaging arising around ∼ 40 kW/cm2. The photoresponse as a function of base-emitter bias dependence does not change with the radiation intensity.

We have evaluated the performance of the InP double heterojunction bipolar transistor and InP-based varactors as a room temperature sensitive detectors for THz computed tomography applications. They were used in transmission mode for the 350 GHz and 650 GHz atmospheric windows.

In this paper, an overview of main results concerning THz detection by nanometer field effect transistors (FETs) and heterojunction based transistors (HBTs) is presented. Different GaInAs/InP and GaN/AlGaN nanometer field effect transistors based detectors are presented. We present also first Silicon C-MOS transistors based integrated circuits for wireless communication in sub-THz range. Special attention is given to transistors based focal plane arrays. We show, how these arrays, together with in purpose developed diffractive 3D printed optics lead to construction of the demonstrators of safety and industrial quality control scanners.

—We present the low frequency noise and the photoresponse in InP double heterojunction bipolar transistor (DHBT) THz detectors. A current responsivity of 0.23 A/W and a noise equivalent power of 4·10-10 W/Hz 1/2 have been measured at 1 kHz modulation frequency. The collector bias can substantially reduce the noise equivalent power.

A graphene ballistic rectifier is used in conjunction with an antenna to demonstrate a rectenna as a terahertz (THz) detector. A small-area (<1 μm2) local gate is used to adjust the Fermi level in the device to optimize the output while minimizing the impact on the cutoff frequency. The device operates in both n- and p-type transport regimes and shows a peak extrinsic responsivity of 764 V/W and a corresponding noise equivalent power of 34 pW Hz–1/2 at room temperature with no indications of a cutoff frequency up to 0.45 THz. The device also demonstrates a linear response for more than 3 orders of magnitude of input power due to its zero threshold voltage, quadratic current–voltage characteristics and high saturation current. Finally, the device is used to take an image of an optically opaque object at 0.685 THz, demonstrating potential in both medical and security imaging applications.

Compact and fast detectors, for imaging and wireless communication applications, require efficient rectification of electromagnetic radiation with frequencies approaching 1 THz and modulation bandwidth up to a few tens of GHz. This can be obtained only by using a mature technology allowing monolithic integration of detectors with low-noise amplifiers. One of the best candidates is indium phosphide bipolar transistor (InP HBT) technology. In this work, we report on room temperature high sensitivity terahertz detection by InP double-heterojunction bipolar transistors (DHBTs) operating in a large frequency range (0.25–3.1 THz). The performances of the DHBTs as terahertz sensors for communications were evaluated showing the modulation bandwidth of investigated DHBTs close to 10 GHz.

Due to their specific physical properties, HgCdTe-based heterostructures are expected to play an important role in terahertz photonic systems. Here, focusing on gated devices presenting inverted band ordering, we evidence an enhancement of the terahertz photoconductive response close to the charge neutrality point and at the magnetic field driven topological phase transition. We also show the ability of these heterostructures to be used as terahertz imagers. Regarding terahertz emitters, we present results on stimulated emission of HgCdTe heterostructures in their conventional semiconductor state above 30 THz, discussing the physical mechanisms involved and promising routes towards the 5–15 THz frequency domain.