Question

What causes the conduction of electricity by semiconductors?

Answer 1

The conduction of electricity in semiconductors occurs due to the movement of free charge carriers, i.e., electrons and holes. This happens by:

1. Thermal Excitation: At room temperature or on heating, some valence electrons gain enough energy to jump into the conduction band, leaving behind holes in the valence band. These electron-hole pairs enable conduction.
2. Doping: Adding small amounts of impurities increases conductivity.
   • n-type Semiconductors: Doping with group 15 elements (e.g., phosphorus) adds free electrons.
   • p-type Semiconductors: Doping with group 13 elements (e.g., boron) creates holes.

Under an electric field, electrons move toward the positive terminal and holes toward the negative terminal, allowing current to flow.