Solid State Physics Devices Electronics

At , the energy bands for conductors, semiconductors, and insulators can be described as follows:
- Conductors: In conductors, the conduction band overlaps with the valence band, meaning electrons can freely move in the material, allowing electrical conduction even at absolute zero temperature.
- Semiconductors: In semiconductors, the valence band is completely filled, and there is a small energy gap (band gap) between the valence band and the conduction band. At , no electrons are in the conduction band.
- Insulators: In insulators, the band gap between the valence band and conduction band is large, and electrons cannot move to the conduction band at , preventing conduction. At room temperature (above ), thermal energy excites some electrons from the valence band to the conduction band, leaving behind holes in the valence band. This creates electron
-hole pairs. These electron
-hole pairs are responsible for electrical conduction in semiconductors. Energy Band Diagram at T = 0 K: