Semiconductor physics

Which correctly describes how the resistivity of an intrinsic semiconductor depends on temperature?

  1. AResistivity decreases as temperature rises
  2. BResistivity increases as temperature rises
  3. CResistivity is constant regardless of temperature
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Answer: A. Resistivity decreases as temperature rises

In an intrinsic semiconductor, the number of carriers excited across the bandgap rises exponentially with temperature, so resistivity falls (a negative temperature coefficient). In metals the carrier count is nearly fixed and lattice-vibration scattering increases, so resistivity rises. NTC thermistors exploit this behavior. Note that in doped silicon near room temperature the carrier count is roughly constant, so there is a range where resistance actually rises as mobility drops.

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More Semiconductor physics questions

  1. In a semiconductor in thermal equilibrium, what is the product of electron density n and hole density p (n×p)? (ni: intrinsic carrier density)
  2. What causes a diffusion current to flow in a semiconductor?
  3. Which is a typical factor that shortens the minority carrier lifetime in silicon?
  4. What is the crystal structure of single-crystal silicon?
  5. What is the drift velocity of electrons with a mobility of 1000 cm²/V·s in an electric field of 100 V/cm?