Image sensors and optical devices

Which photosensitive material is being researched and commercialized to detect short-wave infrared (SWIR, about 1 to 2 µm), which silicon cannot detect, with low-cost image sensors?

  1. AFilms of colloidal quantum dots such as PbS
  2. BSilicon dioxide
  3. CAluminum
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Answer: A. Films of colloidal quantum dots such as PbS

Colloidal quantum dots such as PbS have a band gap that can be tuned by particle size, and they can be coated from solution to form a film directly on a readout-circuit chip. They are therefore being researched and commercialized as a way to make SWIR image sensors more cheaply than expensive InGaAs sensors.

  • A. Correct. Quantum-dot films detect SWIR.
  • B. Silicon dioxide is an insulator and is not used as an infrared absorber.
  • C. Aluminum is a metal used for wiring and the like.
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