Semiconductor physics

In a semiconductor in thermal equilibrium, what is the product of electron density n and hole density p (n×p)? (ni: intrinsic carrier density)

  1. AIt is always 0
  2. BIt equals ni squared
  3. CIt equals the square of the impurity concentration
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Answer: B. It equals ni squared

In thermal equilibrium, n × p = ni² holds even with doping (the law of mass action). For example, if donors increase the electron density n, the hole density p decreases correspondingly. This relationship is often used to calculate minority carrier density.

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More Semiconductor physics questions

  1. What causes a diffusion current to flow in a semiconductor?
  2. Which is a typical factor that shortens the minority carrier lifetime in silicon?
  3. What is the crystal structure of single-crystal silicon?
  4. What is the drift velocity of electrons with a mobility of 1000 cm²/V·s in an electric field of 100 V/cm?
  5. What is the mass introduced so that the motion of an electron in a crystal can be treated like that of a free electron in response to external forces?