13.1.1 Understanding intrinsic and extrinsic semiconductors

• Intrinsic semiconductors have an equal number of electrons and holes in their crystal lattice.


  True
• The lowest unoccupied energy level in intrinsic semiconductors is called the conduction band.
• What is the primary process of charge carrier generation in intrinsic semiconductors?

  Thermal excitation
• What is the process called that creates extrinsic semiconductors?

  Doping
• What dopant is commonly used to create p-type semiconductors?

  Boron
• There are two types of extrinsic semiconductors: N-type and P-type
• Why does doping with phosphorus increase the conductivity of silicon in N-type semiconductors?

  Extra electrons
• What are the minority carriers in P-type semiconductors?

  Electrons
• Arrange the energy bands in intrinsic semiconductors from highest to lowest energy levels:

  1️⃣ Conduction Band

  2️⃣ Energy Gap

  3️⃣ Valence Band
• In intrinsic semiconductors, charge carriers are generated primarily via thermal excitation
• How are extrinsic semiconductors created?

  By doping
• The dopant in P-type semiconductors is typically boron
• In p-type semiconductors, holes are the majority charge carriers.


  True
• P-type semiconductors increase conductivity by creating holes in the valence band.

  True
• In p-type semiconductors, acceptor impurities create holes
• Intrinsic semiconductors have low conductivity at room temperature
• Match the material type with its energy band properties:

  Insulator ↔️ Large energy gap

  Semiconductor ↔️ Small energy gap

  Conductor ↔️ No energy gap
• What type of dopant is used to create n-type semiconductors?

  Phosphorus
• What materials are commonly used in intrinsic semiconductors?

  Silicon or germanium
• What is the highest occupied energy level in intrinsic semiconductors called?

  Valence band
• Match the material type with its energy band characteristics:

  Insulator ↔️ Large energy gap

  Semiconductor ↔️ Small energy gap

  Conductor ↔️ No energy gap
• Increasing the temperature of an intrinsic semiconductor increases the concentration of both electrons and holes.


  True
• Electrons are the majority carriers in n-type semiconductors.

  True
• What is the process called that modifies the electrical properties of an intrinsic semiconductor by adding impurities?

  Doping
• Electrons are the majority carriers in N-type semiconductors.


  True
• Match the dopant with the type of extrinsic semiconductor it creates:

  Phosphorus ↔️ N-type

  Boron ↔️ P-type
• How does temperature affect the conductivity of intrinsic semiconductors?

  Increases conductivity
• What is the conductivity of semiconductors at room temperature compared to insulators?

  Low
• Increasing the temperature of an intrinsic semiconductor increases both electron and hole concentrations.


  True
• P-type semiconductors have electrons as the majority carriers.

  False
• In n-type semiconductors, electrons are the majority charge carriers
• What band are electrons added to in n-type semiconductors?

  Conduction band
• What effect do donor impurities have on electron conductivity in n-type semiconductors?

  Increases electron conductivity
• What are examples of intrinsic semiconductors?

  Silicon or Germanium
• The energy gap in semiconductors is smaller than in insulators.


  True
• The number of electrons and holes in intrinsic semiconductors is always equal.


  True
• Match the extrinsic semiconductor type with its properties:

  N-type ↔️ Electrons as majority carriers

  P-type ↔️ Holes as majority carriers
• What is the process called that creates extrinsic semiconductors?

  Doping
• What type of majority carriers do P-type semiconductors have?

  Holes
• Intrinsic semiconductors have charge carrier concentrations that depend on temperature.

  True