Semiconductors

Definition

Semiconductors are materials that have electrical conductivity between that of conductors and insulators. They play a crucial role in modern electronics, as they can be manipulated to control electrical current, making them essential for devices like diodes, transistors, and lasers. Their unique properties allow for the absorption of light and spontaneous emission, contributing significantly to the functionality of various optical and electronic devices.

5 Must Know Facts For Your Next Test

1. Semiconductors exhibit a phenomenon called 'band gap,' which allows them to conduct electricity under certain conditions while acting as insulators under others.
2. In laser applications, semiconductors can undergo stimulated emission when excited by an external light source, enabling the generation of coherent light.
3. The absorption spectrum of semiconductors is crucial for understanding their behavior in photonic devices, as it dictates how they interact with light at various wavelengths.
4. Semiconductors can create laser-induced plasma when subjected to high-intensity laser light, which causes rapid ionization and energetic electron interactions.
5. The efficiency of semiconductor lasers is highly dependent on temperature, as changes in temperature can affect their threshold current and overall performance.

Review Questions

• How do the unique properties of semiconductors enable their use in controlling electrical currents?
  • Semiconductors possess a band gap that allows them to behave as insulators or conductors depending on external conditions such as temperature and doping. This ability to control electrical conductivity makes them ideal for creating devices that manage electrical current flow, like transistors and diodes. By adjusting the concentration of charge carriers through doping, semiconductor materials can be tailored to meet specific electronic requirements.
• Discuss the process and significance of stimulated emission in semiconductor lasers.
  • Stimulated emission occurs when excited electrons in a semiconductor return to a lower energy state, emitting photons that are coherent with the stimulating light. This process is fundamental to the operation of semiconductor lasers, as it leads to the amplification of light within the laser medium. The ability of semiconductors to undergo this process enables them to produce highly focused and powerful laser beams used in numerous applications.
• Evaluate the implications of laser-induced plasma formation in semiconductors and its relevance to material processing.
  • Laser-induced plasma formation in semiconductors occurs when high-intensity laser pulses ionize the material, creating a state where electrons are free from their atomic bonds. This phenomenon has significant implications for material processing, including ablation techniques used in microfabrication and surface modification. The ability to precisely control laser parameters allows for tailored material responses, enabling advances in manufacturing and technology development.

Related terms

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

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

P-N Junction: A junction formed by joining p-type and n-type semiconductors, which is critical for the operation of diodes and transistors.