Semiconductors

Definition

Semiconductors are materials that have electrical conductivity between that of conductors and insulators, typically used in electronic devices. They can be manipulated to control the flow of electrical current, which is crucial for the operation of modern electronics such as diodes, transistors, and integrated circuits. The unique properties of semiconductors allow them to exhibit behaviors like rectification and amplification, which directly relate to electric current, current density, resistance, and Ohm's law.

5 Must Know Facts For Your Next Test

1. Semiconductors can be classified as intrinsic (pure) or extrinsic (doped) based on their level of impurity and conductivity.
2. At absolute zero temperature, semiconductors behave like insulators because there are no free charge carriers available for conduction.
3. Temperature plays a significant role in the conductivity of semiconductors; as temperature increases, more electrons can jump into the conduction band.
4. The relationship between current density and electric field in semiconductors is nonlinear, especially when reaching high electric fields.
5. Ohm's law applies differently to semiconductors since their resistance changes with applied voltage and temperature.

Review Questions

• How does the process of doping affect the conductivity of semiconductors?
  • Doping involves adding specific impurities to a semiconductor material to change its electrical properties. By introducing donor or acceptor atoms into the semiconductor lattice, the number of free charge carriers increases or decreases. This process allows for enhanced control over the material's conductivity, making it possible to create p-type (positive) or n-type (negative) semiconductors that are essential for various electronic components.
• In what ways do the unique properties of semiconductors influence their applications in electronic devices related to resistance and current density?
  • Semiconductors have a distinct ability to control electrical current through their variable conductivity. This allows them to function in devices where precise control of current density is required. For example, in transistors, the conductivity can be modulated by applying a voltage, enabling them to switch between conducting and insulating states. This property is fundamental in understanding how resistance behaves in these devices, especially since Ohm's law doesn't apply linearly under varying conditions.
• Evaluate the implications of temperature changes on semiconductor performance in relation to Ohm's law.
  • Temperature significantly impacts semiconductor performance by influencing charge carrier mobility and density. As temperature rises, more electrons gain enough energy to transition from the valence band to the conduction band, leading to increased conductivity. This behavior deviates from Ohm's law since the resistance of a semiconductor isn't constant; it changes with both temperature and applied voltage. Understanding this relationship is crucial when designing circuits that utilize semiconductors, as it affects overall device efficiency and reliability.

Related terms

Conductivity: The ability of a material to conduct electric current, which depends on the availability of charge carriers and their mobility.

Doping: The process of adding impurities to a semiconductor to alter its electrical properties, enhancing its conductivity.

Band Gap: The energy difference between the valence band and conduction band in a semiconductor, determining its electrical properties and the energy required for charge carriers to move.