Semiconductor

Definition

A semiconductor is a material that has electrical conductivity between that of a conductor, such as metal, and an insulator, such as glass or ceramic. Semiconductors are the foundation of modern electronics, enabling the development of devices like transistors, integrated circuits, and microprocessors.

5 Must Know Facts For Your Next Test

1. Semiconductors can have their electrical properties tuned by the addition of impurities through a process called doping.
2. The p-n junction, formed by the interface between p-type and n-type semiconductors, is the fundamental building block of many semiconductor devices.
3. The bandgap energy of a semiconductor determines its ability to absorb and emit photons, making semiconductors useful in optoelectronic applications.
4. Silicon and germanium are the most commonly used semiconductor materials, though newer materials like gallium arsenide and silicon carbide are also widely used.
5. Semiconductors are the foundation of modern electronics, enabling the development of transistors, integrated circuits, and microprocessors that power a vast array of electronic devices.

Review Questions

• Explain how the electrical conductivity of semiconductors is different from that of conductors and insulators.
  • Semiconductors have an electrical conductivity that falls between that of conductors and insulators. Unlike conductors, which have a high density of free electrons that can easily move through the material, semiconductors have a lower density of charge carriers. However, unlike insulators, which have a large energy gap between their valence and conduction bands, semiconductors have a smaller bandgap that allows for the promotion of electrons from the valence band to the conduction band, enabling some degree of electrical conductivity. This intermediate conductivity is what makes semiconductors so useful in electronic applications, as their properties can be easily tuned and controlled.
• Describe the role of doping in modifying the electrical properties of semiconductors.
  • Doping is the process of intentionally introducing impurities into a semiconductor material to alter its electrical properties. By adding small amounts of impurities, such as boron or phosphorus, to a semiconductor like silicon, the concentration and type of charge carriers (electrons or holes) can be increased or decreased. This allows for the creation of p-type and n-type semiconductors, which form the basis of many semiconductor devices, such as diodes and transistors. The ability to precisely control the electrical properties of semiconductors through doping is a key factor in the development of modern electronics and the wide range of semiconductor-based applications.
• Analyze how the bandgap energy of a semiconductor material affects its optical and electrical properties.
  • The bandgap energy of a semiconductor is a fundamental property that determines its behavior and suitability for various applications. A smaller bandgap, such as in silicon or germanium, allows for the promotion of electrons from the valence band to the conduction band with relatively little energy input, making these materials suitable for electronic devices that operate at lower voltages. Conversely, semiconductors with larger bandgaps, like gallium arsenide or silicon carbide, require more energy to excite electrons across the bandgap, but this also makes them better suited for high-power, high-frequency, and high-temperature applications. Additionally, the bandgap energy directly influences a semiconductor's ability to absorb and emit photons, which is crucial for optoelectronic devices like LEDs, solar cells, and photodetectors. By carefully selecting semiconductor materials with the appropriate bandgap, engineers can optimize the performance of a wide range of electronic and photonic devices.

Related terms

Doping:

The process of intentionally introducing impurities into a semiconductor material to alter its electrical properties, such as increasing the number of charge carriers.

P-N Junction: The interface between a p-type semiconductor and an n-type semiconductor, which forms the basis of many semiconductor devices like diodes and transistors.

Bandgap: The energy difference between the valence band and the conduction band in a semiconductor, which determines the material's electrical and optical properties.