Intrinsic semiconductor

Definition

An intrinsic semiconductor is a pure semiconductor material that has no significant impurities and exhibits electrical conductivity based solely on its own charge carriers, namely electrons and holes. The unique band structure of intrinsic semiconductors shows a valence band fully occupied with electrons and a conduction band that is empty at absolute zero, allowing for conductivity to increase as temperature rises due to thermally generated electron-hole pairs.

5 Must Know Facts For Your Next Test

1. Intrinsic semiconductors have an equal number of electrons and holes at thermal equilibrium, which means they are intrinsic to their own crystal structure.
2. Common examples of intrinsic semiconductors include silicon (Si) and germanium (Ge), which have favorable electronic properties for device applications.
3. As temperature increases, more electrons gain enough energy to jump from the valence band to the conduction band, increasing the conductivity of intrinsic semiconductors.
4. The intrinsic carrier concentration in semiconductors is highly temperature-dependent; as temperature rises, the number of charge carriers increases exponentially.
5. Intrinsic semiconductors are essential for understanding the behavior of doped semiconductors, as they provide a baseline for how impurities will alter electrical properties.

Review Questions

• How does temperature affect the conductivity of intrinsic semiconductors?
  • Temperature has a significant impact on the conductivity of intrinsic semiconductors. As the temperature increases, more electrons gain enough thermal energy to move from the valence band to the conduction band, resulting in an increased concentration of free charge carriers. This process leads to higher electrical conductivity because both electrons and holes contribute equally to current flow in an intrinsic semiconductor.
• Compare and contrast intrinsic and extrinsic semiconductors in terms of their charge carrier dynamics.
  • Intrinsic semiconductors have charge carriers that are generated solely from their pure crystal structure, with equal numbers of electrons and holes at thermal equilibrium. In contrast, extrinsic semiconductors are doped with specific impurities that introduce additional charge carriers, leading to an imbalance between electrons and holes. This doping enhances conductivity beyond what can be achieved through thermal excitation alone, making extrinsic semiconductors more widely used in practical applications like transistors and diodes.
• Evaluate the role of intrinsic semiconductors in the development of modern electronic devices and their fundamental significance in semiconductor physics.
  • Intrinsic semiconductors serve as the foundational building blocks for modern electronic devices, such as diodes and transistors. Their understanding is crucial for semiconductor physics because they establish baseline characteristics like carrier concentration and mobility. By studying intrinsic materials, scientists can determine how various doping methods impact electrical properties and performance in practical applications. This knowledge is essential for designing efficient electronic components that leverage both intrinsic behavior and doped enhancements.

Related terms

Extrinsic Semiconductor: A semiconductor that has been doped with impurities to enhance its electrical conductivity by introducing additional charge carriers.

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

Charge Carrier: Particles, such as electrons or holes, that carry electric charge in a semiconductor, contributing to its conductivity.