Photonics Dictionary


A semiconductor is a type of material that has electrical conductivity between that of a conductor and an insulator. In other words, semiconductors have properties that are intermediate between metals (good conductors of electricity) and insulators (poor conductors of electricity). The conductivity of a semiconductor can be controlled and modified by factors such as temperature, impurities, or an applied electric field.

The most common semiconductors are crystalline solids, and they are typically composed of elements from groups III and V or groups II and VI of the periodic table. Silicon (Si) and germanium (Ge) are two of the most widely used semiconductors in electronic devices.

Key characteristics of semiconductors include:

Conductivity: Semiconductors have a conductivity level between that of conductors and insulators. Their conductivity can be altered by factors such as temperature, light, or the addition of certain impurities.

Energy band gap: Semiconductors have a small energy band gap between their valence band (filled with electrons) and their conduction band (where electrons can move freely). The energy required to move an electron from the valence band to the conduction band is often in the range of visible or near-infrared light.

Doping: The conductivity of semiconductors can be modified through a process called doping, where specific impurities are intentionally introduced into the crystal structure. Doping introduces extra charge carriers, either electrons or holes (positively charged vacancies), which affect the material's overall conductivity.

Semiconductors play a crucial role in modern electronics. Semiconductor devices, such as transistors, diodes, and integrated circuits, form the foundation of electronic circuits in computers, smartphones, sensors, and a wide range of other electronic devices. The ability to control the electrical properties of semiconductors has led to the development of the semiconductor industry, which is a cornerstone of the global electronics market.

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