Multiple choice

N-type semiconductors are obtained by adding impurities to pure germanium. These impurities have to be

  1. monovalent

  2. trivalent

  3. tetravalent

  4. pentavalent

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

N-type semiconductors are created by doping pure silicon or germanium with pentavalent (5 valence electrons) impurities like phosphorus or arsenic. These provide extra free electrons, making the material negative-type.