Abstract-InP double heterojunction bipolar transistors for terahertz computed tomography

AIP Advances

Dominique Coquillat, Alexandre Duhant, Meriam Triki, Virginie Nodjiadjim, Agnieszka Konczykowska, Muriel Riet, Nina Dyakonova, Olivier Strauss, Wojciech Knap

(a) Schematic of the InP DHBT THz detector and read-out circuit connections. (b) Input characteristics IBE − VBE of the 3-finger device. Inset: SEM photograph of a 3-finger DHBT with 3 × 10 μm × 0.7 μm emitter area. (c) Photo-voltage ΔU (left hand scale) and area normalized voltage responsivity RmeasV$R_V^{meas}$ (right hand scale) as a function of frequency for VBE = 0.43 V.

https://aip.scitation.org/doi/abs/10.1063/1.5039331

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.

US Patent-Impedance adaptation in a THz detector

United States Patent 9614116
Inventors:

Le Bars, Philippe (Thorigne Fouillard, FR) 
Sahyoun, Walaa (Rennes, FR) 
Knap, Wojciech (Saint-Gely-du-Fesc, FR) 
Diakonova, Nina (Montpellier, FR) 
Coquillat, Dominique (Prades-le-Lez, FR) 

http://www.freepatentsonline.com/9614116.html

At least one electronic device, system and method of manufacturing an electromagnetic wave detector are provided herein. The electronic device for receiving at least one electromagnetic wave of a given frequency may comprise at least one first field effect transistor, and at least one antenna configured to receive the at least one electromagnetic wave and connected to a gate of the at least one first field effect transistor, wherein a length of the gate is in a same order of magnitude as an oscillation length of an oscillation regime of the at least one first field effect transistor at the given frequency, and a width of the gate is such that an impedance presented by the at least one first field effect transistor in the oscillation regime is adapted to an impedance of the at least one antenna.

Abstract-Improvement of terahertz field effect transistor detectors by substrate thinning and radiation losses reduction

Dominique Coquillat, Jacek Marczewski, Pawel Kopyt, Nina Dyakonova, Benoit Giffard, and Wojciech Knap
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-24-1-272

Phenomena of the radiation coupling to the field effect transistors based terahertz (THz) detectors are studied. We show that in the case of planar metal antennas a significant portion of incoming radiation, instead of being coupled to the transistors, is coupled to an antenna substrate leading to responsivity losses and/or cross-talk effects in the field effect based THz detector arrays. Experimental and theoretical investigations of the responsivity versus substrate thickness are performed. They clearly show how to minimize the losses by the detector/ array substrate thinning. In conclusion simple quantitative rules of losses minimization by choosing a proper substrate thickness of field effect transistor THz detectors are presented for common materials (Si, GaAs, InP, GaN) used in semiconductor technologies.

© 2016 Optical Society of America

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