Wavelength and polarization selective multi-band tunnelling quantum dot detectors |
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Authors: | A G U Perera G Ariyawansa V M Apalkov S G Matsik X H Su S Chakrabarti P Bhattacharya |
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Institution: | (1) Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303, USA;(2) Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109-2122, USA |
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Abstract: | The reduction of the dark current without reducing the photocurrent is a considerable challenge in developing far-infrared
(FIR)/terahertz detectors. Since quantum dot (QD) based detectors inherently show low dark current, a QD-based structure is
an appropriate choice for terahertz detectors. The work reported here discusses multi-band tunnelling quantum dot infrared
photo detector (T-QDIP) structures designed for high temperature operation covering the range from mid-to far-infrared. These
structures grown by molecular beam epitaxy consist of a QD (InGaAs or InAlAs) placed in a well (GaAs/AlGaAs) with a double-barrier
system (AlGaAs/InGaAs/AlGaAs) adjacent to it. The photocurrent, which can be selectively collected by resonant tunnelling,
is generated by a transition of carriers from the ground state in the QD to a state in the well coupled with a state in the
double-barrier system. The double-barrier system blocks the majority of carriers contributing to the dark current. Several
important properties of T-QDIP detectors such as the multi-colour (multi-band) nature of the photoresponse, the selectivity
of the operating wavelength by the applied bias, and the polarization sensitivity of the response peaks, are also discussed. |
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Keywords: | multi band IR detectors quantum dot resonant tunnelling polarization |
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