Question

Describe the two main types of semiconductors and mention their important applications.

Answer 1

The two main types of semiconductors are:

1. Intrinsic Semiconductors:
   1. Intrinsic semiconductors are pure semiconductors without any added impurities; their conductivity depends entirely on the thermal excitation of electrons across the band gap.
   2. These are pure semiconductors without any added impurities.
   3. Their conductivity depends entirely on the thermal excitation of electrons across the band gap.
   4. Examples include pure silicon (Si) and germanium (Ge).
   5. It is used in temperature sensors, photodetectors, and as the base material for making extrinsic semiconductors.
2. Extrinsic Semiconductors:
   1. Extrinsic semiconductors are doped with small amounts of impurities to increase their conductivity.
   2. There are two subtypes:
      1. n-type: Doped with elements having more valence electrons (e.g., phosphorus in silicon) to add extra electrons as charge carriers.  
      2. p-type: Doped with elements having fewer valence electrons (e.g., boron in silicon) to create holes as positive charge carriers. 
   3. These elements are widely used in diodes, transistors, solar cells, LEDs, and integrated circuits (ICs).