Abstract-Asymmetric dual-grating gates graphene FET for detection of terahertz radiations

APL Photonics

J. A. Delgado-Notario, V. Clericò, E. Diez. J. E. Velázquez-Pérez. T. Taniguchi,  K. Watanabe. T. Otsuji,  Y. M. Meziani,

(a) Optical image of the ADGG-GFET and (b) zoomed image of the detector showing the central active region of the THz detector where drain (D), source (S), and top gates (TG1 and TG2) have been labeled. (c) 3D schematic view of the ADGG-GFET and (d) drain-to-source resistance vs back-gate voltage in the 4–300 K temperatures range. The charge neutrality point (CNP) was found to be close to VBG ≈ −5.8 V.

https://aip.scitation.org/doi/full/10.1063/5.0007249

A graphene-based field-effect-transistor with asymmetric dual-grating gates was fabricated and characterized under excitation of terahertz radiation at two frequencies: 0.15 THz and 0.3 THz. The graphene sheet was encapsulated between two flakes of h-BN and placed on a highly doped SiO2/Si substrate. An asymmetric dual-grating gate was implemented on the h-BN top flake. Even though no antenna was used to couple the incoming radiation, a clear gate-bias-dependent photocurrent was measured under excitation at 0.3 THz up to room temperature. We subsequently demonstrated that the device can be used for terahertz sensing and inspection of hidden metallic objects at room temperature.

Abstract-Continuous Wave Terahertz Sensing Using GaN HEMTs

Elham Javadi, Juan Antonio Delgado Notario, Nasser Masoumi, Y. M. Meziani, 

https://www.researchgate.net/publication/324264744_Continuous_Wave_Terahertz_Sensing_Using_GaN_HEMTs

A commercial GaN high electron mobility transistor (HEMT) is investigated as efficient detector of terahertz radiations. Enhancement of the photoresponse in excess of one order of magnitude (up to 1 kV W−1) is obtained when a constant drain‐to‐source current is applied. The photoresponse remains unchanged with chopping frequency up to 5 kHz demonstrating a high‐speed response of GaN HEMT detectors. It is demonstrated that the bounding wires play an important role to couple terahertz radiations to the channel of the device. Terahertz imaging of hidden objects by using GaN HEMTs as a sensor is also demonstrated. GaN high electron mobility transistor (HEMT) is used as an efficient detector of terahertz radiations with good responsivity. Terahertz imaging of hidden objects is obtained using the GaN HEMTs as a sensor. This open the way for new compact terahertz system for inspection and imaging applications.

Abstract-Detection of terahertz radiation using submicron field effect transistors and their use for inspection applications

J. A. Delgado Notario,  E. Javadi,  J. E. Velázquez,  E. Diez,  Y. M. Meziani,  K. Fobelets,

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10439/1043907/Detection-of-terahertz-radiation-using-submicron-field-effect-transistors-and/10.1117/12.2278208.pdf?SSO=1

We investigated room temperature detection of terahertz radiation by using two different types of transistors (Strained Silicon Modulation field effect transistor, GaAs PHEMT). Experimental results show a good level of response under excitation at 0.3 THz. Competitive performance parameters were obtained (NEP and responsivity) in comparison with other detectors. Enhancement of the photoresponse signal by imposing a dc drain-to-source current (I_ds) was observed experimentally. Inspection of hidden objects by using those devices within a terahertz imaging setup was demonstrated at 300 GHz and a better image was obtained under I_ds.

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