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Proceedings Paper

Wave packet simulations of escape and capture probabilities in multiquantum-well infrared detectors
Author(s): Abraham Fraenkel; Yoram Betser; Elieser Finkman; Gad Bahir
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Paper Abstract

There are several responsivity and gain models adequate to MQW detectors. All are related to two fundamental properties: the escape efficiency of a photo-excited carrier out of the well boundary (Pout) and the capture (or crossing) probability (Pc or Pw equals 1-Pc). In this work we present a rigorous calculation of the escape and capture probabilities based on a Quantum Mechanical approach. In this vicinity of the well the electrons are treated as Gaussian Wave-Packets. The simulation calculates the quantum mechanical reflections encountered by the packets at the interfaces as a function of kinetic energy and applied electric field. The relaxation processes into the bound sub-level are taken into account by introducing an imaginary potential. The simulations are carried out on both stepped and rectangular structures. The step reduces the dwell time above the well and hence the capture probability. This result is in good qualitative agreement with responsivity measurements on such structures. The effects of interface charge and non-uniform charge distribution are also considered. We assume an accumulation of negative sheet charge on the `inverted' interface facing the substrate. This excess charge, introduced during the growth sequence, induces structural asymmetry. The modified well potential is calculated self-consistently and results in an increased barrier height for carriers propagating towards the substrate. Those results are consistent with the asymmetrical responsivity and noise characteristics measured by various groups.

Paper Details

Date Published: 7 October 1994
PDF: 11 pages
Proc. SPIE 2274, Infrared Detectors: State of the Art II, (7 October 1994); doi: 10.1117/12.189242
Show Author Affiliations
Abraham Fraenkel, Semi-Conductor Devices (Israel)
Yoram Betser, Technion--Israel Institute of Technology (Israel)
Elieser Finkman, Technion--Israel Institute of Technology (Israel)
Gad Bahir, Technion--Israel Institute of Technology (Israel)

Published in SPIE Proceedings Vol. 2274:
Infrared Detectors: State of the Art II
Randolph E. Longshore, Editor(s)

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