Semiconductor physics

How many valence (outermost-shell) electrons does a silicon atom have?

  1. A5
  2. B4
  3. C3
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Answer: B. 4

Silicon is a group IV (group 14) element and has four valence electrons. In the crystal, each atom shares its valence electrons with four neighboring atoms to form covalent bonds. Boron (group III) has three valence electrons and phosphorus (group V) has five; they act as an acceptor and a donor, respectively.

  • A. Five valence electrons is the case for group V elements such as phosphorus and arsenic.
  • B. Correct. As a group IV element, silicon has four valence electrons.
  • C. Three valence electrons is the case for group III elements such as boron.
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More Semiconductor physics questions

  1. Which statement is correct when boron (B) is added to silicon as an impurity?
  2. What are the majority carriers in a p-type semiconductor?
  3. Which of the following materials has the largest band gap?
  4. Which is the correct unit of carrier mobility?
  5. With electron density n, hole density p, electron mobility μn, hole mobility μp and elementary charge q, which expression gives the conductivity σ of a semiconductor?