Compound semiconductors

Which correctly describes the quantum well structure used in the light-emitting layers of semiconductor lasers and LEDs?

  1. AA very thin layer with a small band gap sandwiched between layers with a larger band gap, confining carriers to increase light-emission efficiency
  2. BA structure with thick metal layers stacked
  3. CA structure without a light-emitting layer
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Answer: A. A very thin layer with a small band gap sandwiched between layers with a larger band gap, confining carriers to increase light-emission efficiency

In a quantum well, carriers are confined in a light-emitting layer only a few nm thick, so electrons and holes meet easily and light is emitted efficiently. The emission wavelength can also be tuned by changing the layer thickness.

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