Semiconductor physics

What causes a diffusion current to flow in a semiconductor?

  1. ACarrier movement due to an electric field
  2. BCarrier deflection due to a magnetic field
  3. CA gradient (difference) in carrier concentration
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Answer: C. A gradient (difference) in carrier concentration

Carriers tend to spread from regions of high concentration to regions of low concentration. The current caused by this concentration gradient is the diffusion current. In contrast, current caused by carriers accelerated by an electric field is called drift current. The balance between these two currents is important in a PN junction.

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More Semiconductor physics questions

  1. Which is a typical factor that shortens the minority carrier lifetime in silicon?
  2. What is the crystal structure of single-crystal silicon?
  3. What is the drift velocity of electrons with a mobility of 1000 cm²/V·s in an electric field of 100 V/cm?
  4. 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?
  5. What does the Fermi level mean?