Intrinsic Semiconductor: An intrinsic semiconductor is a pure semiconductor material, such as silicon or germanium, that has no impurities added to it. Intrinsic semiconductors have a characteristic band gap energy, which is the energy required to promote an electron from the valence band to the conduction band. Intrinsic semiconductors have a band gap that is small enough to allow thermal excitation of electrons from the valence band to the conduction band at room temperature.

In an intrinsic semiconductor, the number of electrons in the conduction band is equal to the number of holes in the valence band. This is because the only source of free electrons and holes in the material is thermal excitation, which creates an equal number of each.

Intrinsic semiconductors can also be doped to create p-type and n-type semiconductors, which are used in electronic devices such as diodes, transistors, and solar cells. When a small amount of impurity atoms are added to an intrinsic semiconductor, it can change the number of free electrons or holes in the material, which creates regions of excess or deficient charge carriers, respectively.

Properties of Intrinsic Semiconductor

Intrinsic semiconductors have several important properties, including:

• Electrical conductivity: Intrinsic semiconductors have a moderate electrical conductivity due to the presence of a small number of free electrons and holes. At room temperature, the electrical conductivity of an intrinsic semiconductor is relatively low compared to that of metals and highly doped semiconductors.
• Energy band structure: Intrinsic semiconductors have a specific energy band structure that includes the valence band, conduction band, and bandgap. The bandgap is the energy required for an electron to move from the valence band to the conduction band, and it determines the material’s ability to conduct electricity.
• Temperature dependence: The conductivity of an intrinsic semiconductor increases with temperature due to the increased thermal excitation of electrons and holes. As the temperature increases, more electrons and holes are excited from the valence band to the conduction band, leading to a higher conductivity.
• Optical properties: Intrinsic semiconductors have interesting optical properties that depend on their band structure. They can absorb light of certain wavelengths, which excites electrons from the valence band to the conduction band and increases the number of free carriers in the material. This property is used in photodetectors and solar cells.
• Minority carrier lifetime: Intrinsic semiconductors have a relatively long lifetime for minority carriers (electrons or holes) that are thermally generated. This is because there are no impurities to recombine the minority carriers and reduce their lifetime. The long minority carrier lifetime makes intrinsic semiconductors useful in high-speed switching and amplification devices.
• Chemical stability: Intrinsic semiconductors are chemically stable because they do not have any impurities that can react with other materials. This property makes them useful in a wide range of applications, including electronic devices and solar cells.

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By Team Learning Mantras