13.1.1 Understanding intrinsic and extrinsic semiconductors

• What are the two types of extrinsic semiconductors?

  N-type and P-type
• At room temperature, electrons in intrinsic semiconductors can break free from covalent bonds to create electron-hole pairs.


  True
• Intrinsic semiconductors have a low electrical conductivity
• What holds the crystalline lattice together in an intrinsic semiconductor?

  Covalent bonds
• The number of electrons and holes in an intrinsic semiconductor is equal.

  True
• What type of element is used to dope n-type semiconductors?

  Pentavalent
• Match the type of semiconductor with its properties:

  N-type ↔️ Primary charge carrier: Electrons

  P-type ↔️ Primary charge carrier: Holes
• The atomic structure of an intrinsic semiconductor consists of a crystalline lattice with covalent bonds between atoms.
• What is the electrical charge of an intrinsic semiconductor?

  Electrically neutral
• What type of bonds hold the crystalline lattice of intrinsic semiconductors together?

  Covalent bonds
• Steps in the formation of extrinsic semiconductors

  1️⃣ Start with an intrinsic semiconductor

  2️⃣ Dope with impurities

  3️⃣ Introduce pentavalent or trivalent elements
• In n-type semiconductors, pentavalent elements donate extra electrons.
• What is the primary charge carrier in p-type semiconductors?

  Holes
• Why do pentavalent impurities in n-type semiconductors increase conductivity?

  Extra free electrons
• What type of impurities are used to form p-type semiconductors?

  Trivalent
• What are intrinsic semiconductors made of?

  Pure semiconductor materials
• The atomic structure of an intrinsic semiconductor consists of a crystalline lattice
• Why is an intrinsic semiconductor electrically neutral?

  Equal number of electrons and holes
• Intrinsic semiconductors are doped with impurities to increase their electrical conductivity.

  False
• The atomic structure of an intrinsic semiconductor is a crystalline lattice with covalent bonds
• What are extrinsic semiconductors doped with to increase conductivity?

  Impurities
• P-type semiconductors are created by doping with trivalent elements to create holes.

  True
• What are intrinsic semiconductors made of?

  Pure semiconductor materials
• At room temperature, electron-hole pairs in intrinsic semiconductors act as charge carriers.


  True
• Intrinsic semiconductors have low electrical conductivity compared to metals.
• Intrinsic semiconductors are electrically neutral due to an equal number of electrons and holes.


  True
• What type of impurities are used to create n-type semiconductors?

  Pentavalent elements
• P-type semiconductors are created by doping with trivalent elements like boron or gallium.


  True
• P-type semiconductors have a net positive charge.
• In p-type semiconductors, holes act as positive charge carriers to increase conductivity.


  True
• Electron holes in p-type semiconductors act as positive charge carriers
• Arrange the following types of semiconductors in order of increasing electrical conductivity:

  1️⃣ Intrinsic semiconductor

  2️⃣ Extrinsic semiconductor

  3️⃣ Metal
• What is the defining characteristic of intrinsic semiconductors?

  Pure material
• Extrinsic semiconductors are created to increase the conductivity of intrinsic semiconductors.


  True
• Intrinsic semiconductors are electrically neutral
• Match the type of extrinsic semiconductor with its primary charge carrier and doping element:

  N-type ↔️ Electrons and Phosphorus

  P-type ↔️ Holes and Boron

  Arsenic ↔️ N-type

  Gallium ↔️ P-type
• n-type semiconductors are doped with pentavalent elements to create extra electrons
• What type of impurities are used to form n-type semiconductors?

  Pentavalent
• What type of doping is used to create p-type semiconductors?

  Trivalent
• N-type semiconductors have a negative charge due to excess electrons.


  True