1
Question
What is a semiconductor? Describe the two main types of semiconductors and contrast their conduction mechanism
Open in App
Solution
Semiconductors are substances with conductance in the intermediate range of 10−6 to 104 ohm−1m−1.
(i) n-type semiconductor: In this semiconductors, increase in conductivity is due to negatively charged electrons. For example, Si or Ge (group 14 elements) doped with P or As (group 15 elements containing 5 valence electrons).
Out of five valence electrons of group 15 elements, 4 valence electrons form covalent bonds with four neighboring Si or Ge atoms and the remaining fifth electron becomes de-localized and increases the conductivity of doped Si or Ge.
(ii) p-type semiconductor. In this semiconductors, increase in conductivity is due to positively charged holes. For example, Si or Ge (group 14 elements) doped with B, Al or Ga (group 13 elements containing 3 valence electrons). In presence of electric field, electrons move toward the positively charged plate through electron holes. However, it appears as if the electron holes are positively-charged and are moving towards the negatively-charged plate.
(i) n-type semiconductor: In this semiconductors, increase in conductivity is due to negatively charged electrons. For example, Si or Ge (group 14 elements) doped with P or As (group 15 elements containing 5 valence electrons).
Out of five valence electrons of group 15 elements, 4 valence electrons form covalent bonds with four neighboring Si or Ge atoms and the remaining fifth electron becomes de-localized and increases the conductivity of doped Si or Ge.
Out of five valence electrons of group 15 elements, 4 valence electrons form covalent bonds with four neighboring Si or Ge atoms and the remaining fifth electron becomes de-localized and increases the conductivity of doped Si or Ge.
(ii) p-type semiconductor. In this semiconductors, increase in conductivity is due to positively charged holes. For example, Si or Ge (group 14 elements) doped with B, Al or Ga (group 13 elements containing 3 valence electrons). In presence of electric field, electrons move toward the positively charged plate through electron holes. However, it appears as if the electron holes are positively-charged and are moving towards the negatively-charged plate.
Suggest Corrections
14
Similar questions