Intrinsic semiconductor

Definition

An intrinsic semiconductor is a pure semiconductor material that has no significant dopant atoms present, which means its electrical properties are determined solely by its own atomic structure. The behavior of intrinsic semiconductors is characterized by a balanced number of electrons and holes at absolute zero temperature, leading to low electrical conductivity. As the temperature increases, more charge carriers are generated, allowing for greater conductivity.

5 Must Know Facts For Your Next Test

1. Intrinsic semiconductors are typically made from silicon or germanium, which have four valence electrons allowing them to form covalent bonds.
2. At absolute zero, intrinsic semiconductors behave as insulators because there are no free charge carriers available for conduction.
3. When intrinsic semiconductors are heated, thermal energy excites some electrons, allowing them to jump from the valence band to the conduction band and create electron-hole pairs.
4. The electrical conductivity of intrinsic semiconductors increases with temperature, as more charge carriers become available for conduction.
5. Intrinsic semiconductors play a crucial role in forming the foundation for all semiconductor devices before any doping processes are applied.

Review Questions

• How does the conductivity of intrinsic semiconductors change with temperature, and what is the underlying mechanism?
  • The conductivity of intrinsic semiconductors increases with temperature because thermal energy allows some electrons to gain enough energy to move from the valence band to the conduction band. This process generates electron-hole pairs, which are essential for electrical conduction. As the number of these charge carriers increases with rising temperature, the material becomes more conductive.
• Compare and contrast intrinsic semiconductors with n-type and p-type semiconductors in terms of their electrical properties and charge carriers.
  • Intrinsic semiconductors are pure materials with equal numbers of electrons and holes, leading to limited conductivity. In contrast, n-type semiconductors have extra electrons due to doping, resulting in an abundance of negative charge carriers, while p-type semiconductors have holes created by doping, leading to more positive charge carriers. These differences in charge carrier concentration significantly affect their conductivity and applications in electronic devices.
• Evaluate the importance of intrinsic semiconductors in the development of modern electronic devices and how they serve as a foundation for further doping processes.
  • Intrinsic semiconductors are vital for modern electronic devices because they provide a baseline for understanding semiconductor behavior before any modifications through doping. They exhibit predictable electrical properties under various conditions, which is crucial for designing devices like diodes and transistors. Understanding intrinsic semiconductors also lays the groundwork for optimizing doping strategies to achieve desired electronic characteristics, making them essential in developing efficient and reliable technology.

Related terms

doping: The process of intentionally introducing impurities into a semiconductor to change its electrical properties, typically by increasing the number of free charge carriers.

n-type semiconductor: A type of semiconductor that has been doped with elements that provide extra electrons, resulting in more negative charge carriers.

p-type semiconductor: A type of semiconductor that has been doped with elements that create holes or vacancies where electrons can be accepted, resulting in more positive charge carriers.