Semiconductor physics

Where is the Fermi level located in an n-type semiconductor?

  1. ACloser to the valence band than the intrinsic Fermi level
  2. BCloser to the conduction band than the intrinsic Fermi level
  3. CAlways inside the valence band
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Answer: B. Closer to the conduction band than the intrinsic Fermi level

In an n-type semiconductor doped with donors, there are many electrons in the conduction band, so the Fermi level shifts from the intrinsic Fermi level near mid-gap toward the conduction band. The higher the donor concentration, the closer it gets. In p-type material it shifts toward the valence band.

Energy band diagram of an n-type semiconductor Conduction band Ec EF (Fermi level) Ei (intrinsic Fermi level) Donors move EF toward Ec Ev Valence band Eg
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More Semiconductor physics questions

  1. Which correctly describes how the resistivity of an intrinsic semiconductor depends on temperature?
  2. In a semiconductor in thermal equilibrium, what is the product of electron density n and hole density p (n×p)? (ni: intrinsic carrier density)
  3. What causes a diffusion current to flow in a semiconductor?
  4. Which is a typical factor that shortens the minority carrier lifetime in silicon?
  5. What is the crystal structure of single-crystal silicon?