Semiconductor physics

What does the Fermi level mean?

  1. AThe energy at the top of the valence band
  2. BThe energy at the bottom of the conduction band
  3. CThe energy at which the probability of occupation by an electron is exactly 1/2
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Answer: C. The energy at which the probability of occupation by an electron is exactly 1/2

The Fermi level is the energy at which the occupation probability in the Fermi-Dirac distribution is 1/2. In an intrinsic semiconductor it lies near mid-gap; it moves toward the conduction band in n-type material and toward the valence band in p-type material. In thermal equilibrium, the Fermi levels of materials in contact line up.

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More Semiconductor physics questions

  1. What is the approximate hole density in n-type silicon with a donor concentration of 1×10¹⁶ cm⁻³ (all donors ionized, intrinsic carrier density ni = 1×10¹⁰ cm⁻³)?
  2. Which light can silicon absorb?
  3. What type of band structure does silicon have?
  4. What can be learned from a Hall effect measurement?
  5. What is a semiconductor called whose impurity concentration is so high that the Fermi level lies inside the conduction or valence band?