Intrinsic semiconductor

Definition

An intrinsic semiconductor is a pure semiconductor material that has an equal number of positive holes and negative electrons at absolute zero temperature. This balance allows intrinsic semiconductors to exhibit unique electrical properties, particularly when external energy is applied, enabling them to conduct electricity under specific conditions.

5 Must Know Facts For Your Next Test

1. Intrinsic semiconductors are typically made from elements like silicon or germanium, which have four valence electrons.
2. At absolute zero, intrinsic semiconductors behave as insulators because there are no free charge carriers available for conduction.
3. When thermal energy is added, electrons can be excited from the valence band to the conduction band, allowing intrinsic semiconductors to conduct electricity.
4. The conductivity of intrinsic semiconductors increases with temperature, as more electrons gain enough energy to jump into the conduction band.
5. Unlike extrinsic semiconductors, intrinsic semiconductors do not have added impurities, making their behavior solely dependent on temperature and intrinsic properties.

Review Questions

• How does temperature affect the electrical conductivity of intrinsic semiconductors?
  • Temperature plays a critical role in the electrical conductivity of intrinsic semiconductors. At absolute zero, there are no free charge carriers, making them behave as insulators. However, as temperature increases, thermal energy can excite electrons from the valence band to the conduction band, creating free electrons and holes that allow for electrical conduction. This temperature-dependent behavior is key to understanding how intrinsic semiconductors function in various applications.
• Compare intrinsic semiconductors with extrinsic semiconductors in terms of their conductivity and composition.
  • Intrinsic semiconductors are composed of pure semiconductor materials with equal numbers of holes and electrons, making their conductivity solely dependent on temperature. In contrast, extrinsic semiconductors are created by doping intrinsic materials with impurities that add either extra electrons (n-type) or holes (p-type), significantly enhancing their conductivity. This distinction highlights how doping alters the electronic properties and performance of semiconductor materials.
• Evaluate the implications of using intrinsic versus extrinsic semiconductors in modern electronic devices.
  • The choice between intrinsic and extrinsic semiconductors has significant implications for modern electronic devices. While intrinsic semiconductors provide a baseline performance based on thermal excitation, they generally exhibit lower conductivity compared to extrinsic counterparts. The use of extrinsic semiconductors allows for precise control over electrical properties through doping, making them more suitable for applications requiring high efficiency and specific conductivity levels. Understanding these differences helps engineers design better devices tailored for various technological needs.

Related terms

Doping: The process of intentionally introducing impurities into a semiconductor to alter its electrical properties, creating extrinsic semiconductors.

Valence Band: The energy band in a solid where the electrons are present and involved in bonding, which is crucial for understanding conductivity in semiconductors.

Band Gap: The energy difference between the valence band and the conduction band in a semiconductor; it determines the material's electrical and optical properties.