Uncooled Detectors Challenges for THz/sub-THz Arrays Imaging
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Uncooled Detectors Challenges for THz/sub-THz Arrays Imaging Fiodor F. Sizov & Vladimir P. Reva & Alexandr G. Golenkov & Vyacheslav V. Zabudsky
Received: 22 December 2010 / Accepted: 5 April 2011 / Published online: 13 April 2011 # Springer Science+Business Media, LLC 2011
Abstract Some problems and challenges for applications of uncooled or slightly cooled detectors (not deeper than to 77 K) for sub-THz and THz (terahertz) arrays are briefly discussed. The possibilities to involve detectors based on plasmon resonance FETs (field effect transistors) and those based on warm electron effect narrow-gap semiconductor bolometers are speculated, as they seem to be promising for using in large format broadband arrays of low-cost systems, though they are still in the stage of research and optimization. Keywords Uncooled THz FET detectors . Bolometers . Performance limits
1 Introduction THz technologies are actively spreading now in different areas of human activity. To be widely used, one of the important components of these technologies are detectors, which require further improvements in their sensitivity at elevated, compared to sub-K operation temperatures. That will make the systems much less complicated and bulky. Historically, THz technologies were mainly used in astrophysics for searching far-infrared and mm radiation (cosmic background), by laser fusion community for plasma diagnostics and in molecular chemistry. They were not widely utilized for commercial (e.g., communication, vision) or military applications because of, to a great extent, the lack of effective emitter and detector technologies, and high atmosphere extinction. Numerous recent breakthroughs in THz technologies have pushed THz researches into the important stage of research activity. THz detectors find a notable role in diverse ranges of applications such as material identification, secured imaging. In the near future, they can become important in short range (but high density) information and communication technologies, or genetic analysis. THz detector technologies still play an increasing role in astrophysics, since THz radiation contains about half of the luminosity of the Universe and F. F. Sizov (*) : V. P. Reva : A. G. Golenkov : V. V. Zabudsky Institute of Semiconductor Physics, Nauki Av., 41, Kiev 03028, Ukraine e-mail: [email protected]
J Infrared Milli Terahz Waves (2011) 32:1192–1206
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almost 98 % of all the photons emitted since the Big Bang [1]. But at the moment uncooled or slightly cooled THz wave instrument capabilities that can be important for low-cost active imaging and spectroscopic applications, are still away in comparison with IR system feasibilities. The number of detectors in the array is a key parameter that determines information capabilities of the system. The accumulation time (or “dwell” time τd) at each sensitive element is proportional to the number Me of sensitive elements in array, and inversely proportional to the frame rate fr, and the number of picture dots M: τd = 1/fr⋅(Me/M). This approach can be app
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