Extrinsic Semiconductor

Definition

An extrinsic semiconductor is a type of semiconductor that has been intentionally doped with impurities to enhance its electrical conductivity. By introducing specific amounts of donor or acceptor atoms, the intrinsic properties of the semiconductor material, typically silicon or germanium, can be modified to create n-type or p-type semiconductors, respectively. This doping process allows extrinsic semiconductors to achieve a greater concentration of charge carriers, making them essential for the functionality of electronic devices.

5 Must Know Facts For Your Next Test

1. Extrinsic semiconductors can be classified into two categories: n-type, which has more electrons, and p-type, which has more holes.
2. The doping concentration in extrinsic semiconductors can significantly affect their conductivity; higher concentrations typically lead to higher conductivity.
3. Common dopants for n-type semiconductors include phosphorus and arsenic, while boron and aluminum are commonly used for p-type semiconductors.
4. The introduction of impurities in extrinsic semiconductors shifts the Fermi level closer to the conduction band in n-types and closer to the valence band in p-types.
5. Extrinsic semiconductors are crucial for creating junctions in devices like diodes and transistors, which are foundational components in modern electronics.

Review Questions

• How does doping change the properties of an intrinsic semiconductor?
  • Doping introduces impurities into an intrinsic semiconductor, significantly altering its electrical properties. This process increases the concentration of charge carriers, either electrons or holes, depending on whether donor or acceptor atoms are used. As a result, the intrinsic material's conductivity improves and transitions it into an extrinsic semiconductor with tailored electrical behavior suitable for various applications.
• Compare and contrast n-type and p-type extrinsic semiconductors in terms of their charge carriers and doping elements.
  • N-type and p-type extrinsic semiconductors differ primarily in their charge carriers. N-type semiconductors have excess electrons due to doping with donor elements like phosphorus, while p-type semiconductors have holes created by doping with acceptor elements like boron. The presence of these different charge carriers impacts how these materials behave in electronic circuits, influencing their conductivity and interaction at junctions.
• Evaluate the significance of extrinsic semiconductors in the development of modern electronic devices.
  • Extrinsic semiconductors are pivotal in the evolution of modern electronic devices as they enable precise control over electrical properties through doping. This adaptability allows engineers to design components like diodes, transistors, and integrated circuits that are fundamental to virtually all electronic technology today. The ability to create n-type and p-type materials facilitates the formation of p-n junctions, which are essential for rectification and amplification in devices ranging from smartphones to computers.

Related terms

Doping: The process of adding impurities to a semiconductor to alter its electrical properties and create n-type or p-type materials.

N-Type Semiconductor: A type of extrinsic semiconductor that has been doped with donor atoms, resulting in an excess of electrons as charge carriers.

P-Type Semiconductor: A type of extrinsic semiconductor that has been doped with acceptor atoms, creating 'holes' that act as positive charge carriers.