NanoVision 2020

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PHYS 2235 Physics of NanoMaterials S. J.
Xu Department of Physics (Lecture 3)
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Quantum Well and Superlattice

• Contents of Lecture 3
• Optical transitions of quantum well
• Absorption of quantum well
• Quantum size effect
• Quantum confined Stark effect
• Emission spectrum of quantum well
• Intersubband transitions in quantum well

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Optical Transitions of QW
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Absorption of QW
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Quantum Size Effect
Low-temperature absorption spectra of various QW
with different well thickness.
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Quantum Confined Stark Effect
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Emission Spectrum of Quantum Well
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Intersubband Transitions in Quantum Well
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Homework 2

• Estimate the temperature at which quantum size
  effect would be important for a semiconductor
  layer of thickness 1 µm if the effective mass of
  the electrons is 0.1 m0.
• Calculate the energy of the first heavy hole
  state of a GaAs/AlGaAs quantum well with width
  d10 nm. Take V00.15 eV, mw0.34 m0 and mb0.5
  m0. How does this energy compare to that of an
  equivalent well with infinite barriers?
• A GaInAs quantum well laser is designed to emit
  at 1.55 µm at room temperature. Estimate the
  width of the quantum well within the device.
  (Eg(GaInAs)0.75eV, me0.041m0, mhh0.47m0, and
  V0 is infinite.)