6. Give examples of point defects in a crystal. Explain what kind of defect is a dopant atom.

Defects in semiconductor crystals are:

  1. Point defects
  2. Line defects
  3. Surface defects
  4. Volume defects

Of point defects, there are native defects (happening without the addition of other atoms) and non-native defects due to contaminants. Native defects are vacancies and self-interstitials. Non-native point defects are substitutions or interstitials. Dopants must be substitution defects.