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Electronic Relaxation and Doping in Small Gap Colloidal Quantum Dots

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Technical Report,31 Mar 2015,30 Mar 2018

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University of Chicago Chicago United States

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Major Goals The major goal of the work is to advance the basic understanding of the infrared optical properties of colloidal quantum dot materials with a view towards applications for photodetection and emission. This is motivated by the need for fast, low cost, low power consumption IR sources and thermal infrared detection for military and civilian applications. While bolometers are getting cheaper, they have lower detectivity and slower response 30Hz than semiconductor detectors. With the present technology, semiconductor detector materials are expensive, grown by MBE, and suffer from Auger recombination, which degrades operation at room temperature. Cooled cameras are very expensive not only because of the requirement for cooling and the infrared optics but also because the active chips are expensive. The use of colloidal quantum dots which may be deposited as thin films on silicon integrated read-out circuits is an alternative approach that could much reduce the cost fabrication. However, the performances of colloidal quantum dots in the infrared have barely started to be investigated. There are many issues toward bringing such materials to a practical end product. The work funded is specifically about two topics First understanding and ultimately controlling the carrier lifetimes, and in particular the exciton and Auger lifetimes. Second understanding and controlling the effect of surface modification on the doping level of the quantum dots. The systems that are investigated are primarily mercury and cadmium chalcogenides quantum dots. For the first aim of the project, we focus on measurement of the mid-infrared photoluminescence of various quantum dots, the efficiencylifetimetemperatureAuger effects, and the role of the environmentligandsmatrix, For the second aim of the project, we focus on measurements of the doping concentrations, the sign of the dopant as a function of particle size, surface and environment.

Subject Categories:

  • Solid State Physics
  • Quantum Theory and Relativity
  • Optics
  • Infrared Detection and Detectors

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