* Energy Bands: The key to understanding semiconductor conductivity lies in the energy bands of their atoms. Electrons in a solid occupy distinct energy levels grouped into bands: the valence band (where electrons are normally bound to atoms) and the conduction band (where electrons are free to move and conduct electricity).
* Energy Gap: There's a gap between these bands called the band gap. This gap represents the energy required for an electron to jump from the valence band to the conduction band.
* Insulators: Insulators have a large band gap, making it extremely difficult for electrons to move freely.
* Conductors: Conductors have a very small or nonexistent band gap, allowing electrons to easily move into the conduction band.
* Semiconductors: Semiconductors have a moderate band gap. At ordinary temperatures, some electrons have enough thermal energy to jump across the gap and move to the conduction band, leading to limited conductivity.
Therefore, at ordinary temperatures, semiconductors exhibit some conductivity due to a few electrons being able to move freely. However, their conductivity is significantly lower than that of conductors.
Key Points:
* Semiconductor conductivity increases with increasing temperature because more electrons gain enough energy to jump into the conduction band.
* The properties of semiconductors are highly dependent on the presence of impurities (doping) which can either increase or decrease their conductivity.
* This unique behavior makes semiconductors ideal for use in transistors, diodes, and other electronic devices.
