Increased responsivity and detectivity in asymmetric quantum-well infrared detectors

Abraham Fraenkel; A. Brandel; Gad Bahir; Elieser Finkman; Gabriela Livescu; Moses T. Asom

doi:10.1117/12.138627

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10 December 1992 Increased responsivity and detectivity in asymmetric quantum-well infrared detectors

Abraham Fraenkel; A. Brandel; Gad Bahir; Elieser Finkman; Gabriela Livescu; Moses T. Asom

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Proceedings Volume 1735, Infrared Detectors: State of the Art; (1992) https://doi.org/10.1117/12.138627
Event: San Diego '92, 1992, San Diego, CA, United States

Abstract

A new type of asymmetric stepped GaAs/AlGaAs multi quantum well infrared detectors is reported. These asymmetric detectors utilize the usual bound to continuum transition. The current responsivity is remarkably asymmetric with regard to the voltage polarity. In contrast with rectangular wells, in which responsivity is saturated in both bias polarities, these wells exhibit saturation only for negative bias. The responsivity increases monotonously with positive electric field. The difference between polarities for the noise is much smaller at low temperatures. As a result, the highest D^* in positive polarity is much higher than in the negative one. This is attributed to changes induced by the field on the transport properties of the excited electrons. In particular, the bias affects the dwell time spent by the carrier wave packet in the well region. Employing this model, we achieve a very good fit with experimental data. The transport asymmetry is further studied using identical asymmetric wells which were grown in opposite sequences. It is shown that the effect of the asymmetry in the interfaces is of the same order of magnitude as the structural asymmetry.

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Abraham Fraenkel, A. Brandel, Gad Bahir, Elieser Finkman, Gabriela Livescu, and Moses T. Asom "Increased responsivity and detectivity in asymmetric quantum-well infrared detectors", Proc. SPIE 1735, Infrared Detectors: State of the Art, (10 December 1992); https://doi.org/10.1117/12.138627

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