Extrinsic semiconductor

Definition

An extrinsic semiconductor is a type of semiconductor that has been doped with specific impurities to enhance its electrical conductivity. This doping introduces additional charge carriers, either electrons or holes, which significantly alter the material's electronic properties and performance. By controlling the type and amount of dopant added, extrinsic semiconductors can be engineered to have tailored conductivity, making them essential for various electronic applications.

5 Must Know Facts For Your Next Test

1. Extrinsic semiconductors can be classified into two categories: n-type (with excess electrons) and p-type (with excess holes), depending on the type of dopant used.
2. Common n-type dopants include phosphorus or arsenic, while p-type dopants often include boron or gallium.
3. The conductivity of an extrinsic semiconductor is highly temperature-dependent, with higher temperatures increasing carrier mobility.
4. Extrinsic semiconductors are fundamental in forming p-n junctions, which are key components in diodes, transistors, and other electronic devices.
5. The concentration of dopants in extrinsic semiconductors is typically much lower than the number of atoms in the semiconductor matrix, allowing for fine-tuning of their electronic properties.

Review Questions

• Compare and contrast intrinsic and extrinsic semiconductors in terms of their electrical properties and applications.
  • Intrinsic semiconductors are pure materials with balanced numbers of electrons and holes, leading to limited conductivity. In contrast, extrinsic semiconductors are doped with impurities to enhance their conductivity significantly by introducing additional charge carriers. The enhanced conductivity of extrinsic semiconductors makes them suitable for various applications like diodes and transistors, while intrinsic semiconductors are mainly used in high-purity applications and basic research.
• Discuss the role of doping in the creation of extrinsic semiconductors and how it affects their electronic behavior.
  • Doping is crucial for creating extrinsic semiconductors as it allows for the intentional introduction of impurities that modify the material's electrical properties. By adding n-type or p-type dopants, the number of free charge carriers is increased, resulting in higher conductivity. This alteration in carrier concentration affects how the material responds to electric fields, enabling devices like diodes to control current flow effectively based on the specific types of charge carriers introduced through doping.
• Evaluate how the understanding of extrinsic semiconductors influences the development of modern electronic devices.
  • Understanding extrinsic semiconductors has been pivotal in advancing modern electronics due to their customizable electrical properties through doping. This knowledge allows engineers to design and fabricate complex electronic devices with precise functionalities. For instance, by optimizing n-type and p-type regions in p-n junctions, technologies such as solar cells, LEDs, and transistors can be engineered for better performance. The ability to manipulate these materials at a molecular level leads to innovations that impact various fields including computing, renewable energy, and telecommunications.

Related terms

intrinsic semiconductor:

A pure semiconductor material without any significant dopants, having an equal number of electrons and holes, which defines its electrical properties.

doping: The process of adding impurities to a semiconductor to change its electrical properties by increasing the number of charge carriers.

p-n junction: A boundary between p-type and n-type semiconductors formed by doping, which is crucial for the operation of many semiconductor devices.