Semiconductor physics

Which light can silicon absorb?

  1. AIt absorbs all wavelengths equally
  2. BLight with energy greater than the band gap (wavelengths shorter than about 1.1 µm)
  3. COnly light with energy smaller than the band gap
Show answer and explanation

Answer: B. Light with energy greater than the band gap (wavelengths shorter than about 1.1 µm)

To excite an electron from the valence band to the conduction band, light needs at least the band-gap energy. Silicon's band gap of about 1.12 eV corresponds to a wavelength of about 1.1 µm; shorter wavelengths are absorbed, while longer-wavelength infrared light mostly passes through.

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More Semiconductor physics questions

  1. What type of band structure does silicon have?
  2. What can be learned from a Hall effect measurement?
  3. What is a semiconductor called whose impurity concentration is so high that the Fermi level lies inside the conduction or valence band?
  4. Which is the Einstein relation between the diffusion coefficient D and the mobility μ of carriers? (k: Boltzmann constant, T: absolute temperature, q: elementary charge)
  5. Which value is closest to the thermal voltage kT/q at room temperature (300 K)?