Semiconductors

Definition

Semiconductors are materials that have electrical conductivity between conductors and insulators. They are essential in modern electronics as they can be manipulated to control the flow of electric current, making them crucial for devices like transistors and diodes. Their unique properties allow them to conduct electricity under certain conditions, especially when influenced by temperature and impurities.

5 Must Know Facts For Your Next Test

1. Semiconductors exhibit a significant temperature dependence of resistance; as temperature increases, the resistance typically decreases due to increased charge carrier movement.
2. Intrinsic semiconductors are pure forms of the material, while extrinsic semiconductors are those that have been doped to enhance their conductivity.
3. Silicon and germanium are the most commonly used semiconductor materials in electronic devices.
4. The behavior of semiconductors is largely governed by the principles of quantum mechanics, particularly concerning energy bands and charge carriers.
5. Temperature affects both the number of free charge carriers and their mobility, which directly influences the overall resistance of a semiconductor.

Review Questions

• How does temperature affect the resistance of semiconductors compared to metals?
  • In semiconductors, resistance decreases as temperature increases due to the increased thermal energy that allows more electrons to jump from the valence band to the conduction band. This behavior contrasts with metals, where resistance typically increases with rising temperature because lattice vibrations impede electron flow. Understanding this difference is crucial for designing electronic components that operate efficiently across varying temperatures.
• Discuss how doping alters the properties of semiconductors and its impact on their electrical behavior.
  • Doping introduces impurities into a semiconductor, significantly altering its electrical properties by increasing its conductivity. This process adds either donor atoms (n-type doping) that provide extra electrons or acceptor atoms (p-type doping) that create holes for electrons to flow. The result is a tailored semiconductor that can efficiently control current flow in devices like diodes and transistors, enabling them to function in various applications.
• Evaluate the role of temperature dependence in the performance of semiconductor devices in real-world applications.
  • The temperature dependence of semiconductors is critical in determining their performance in practical applications. For instance, as temperatures rise, semiconductor devices may experience decreased resistance and increased leakage currents, impacting their reliability and efficiency. This phenomenon necessitates careful thermal management in devices like microprocessors and power electronics, where fluctuations in operating temperature can lead to failure or degradation over time. Understanding these effects helps engineers design robust systems that maintain performance across various environmental conditions.

Related terms

Conductivity:

The ability of a material to conduct electric current, which is influenced by factors such as temperature and the presence of impurities.

Doping: The process of adding impurities to a semiconductor to change its electrical properties, enhancing its conductivity.

Band Gap: The energy difference between the valence band and the conduction band in a semiconductor, which determines its electrical properties.