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1 Opto-Electronics Review

1 2007

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Wavelength and polarization selective multi-band tunnelling quantum dot detectors

Perera A. G. U., Ariyawansa G., Apalkov V. M., Matsik S. G., Su X. H., Chakrabarti S., Bhattacharya P.

Opto-Electronics Review

2007

Vol. 15, No. 4

223-228

The reduction of the dark current without reducing the photocurrent is a considerable challenge is 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.