Worksheet: Pure Semiconductors

In this worksheet, we will practice describing the electrical bonds in pure semiconductor materials.

Q1:

The diagram below shows a lattice of Si atoms where a free electron is adjacent to a vacancy. Which of the following diagrams most correctly represents the lattice a short time later?

  • A
  • B
  • C
  • D
  • E

Q2:

In a pure semiconductor at a temperature of 320 K, the number of free electrons in the semiconductor is 𝑛. The temperature of the semiconductor is increased to 420 K. Which of the following correctly describes how 𝑛 changes? The semiconductor is in thermal equilibrium at both temperatures.

  • A𝑛 remains constant.
  • B𝑛 increases.
  • C𝑛 decreases.

Q3:

The following diagrams show a lattice of Si atoms. Which of the diagrams shows the lattice at a higher temperature?

  • A
  • B
  • CBoth diagrams show the lattice at the same temperature.

Q4:

In a pure semiconductor at a temperature of 320 K, the rate at which electrons in the semiconductor become free electrons is 𝑛 and the rate at which holes form in the semiconductor is 𝑛. The temperature of the semiconductor is reduced to 280 K. What is the ratio of 𝑛 to 𝑛? The semiconductor is in thermal equilibrium at both temperatures.

Q5:

In a pure semiconductor at a temperature of 320 K, the number of free electrons in the semiconductor is 𝑛 and the number of holes in the semiconductor is 𝑛. The temperature of the semiconductor is reduced to 280 K. What is the ratio of 𝑛 to 𝑛? The semiconductor is in thermal equilibrium at both temperatures.

Q6:

In a lattice of Si atoms, an electron in the outermost shell of an atom gains sufficient energy to become a free electron, leaving a vacancy in the shell. The vacancy is then filled by a different electron. Which of the following could be the source of the electron that fills the vacancy?

  • AA bound electron from a shell other than the outermost shell of the atom from which the free electron was produced
  • BA bound electron from a shell other than the outermost shell of an atom bonded with the atom from which the free electron was produced
  • CA bound electron from the outermost shell of an atom bonded with the atom from which the free electron was produced
  • DA bound electron from the outermost shell of the atom from which the free electron was produced
  • EAnother free electron in the lattice

Q7:

In a lattice of Si atoms, an electron in the outermost shell of an atom gains sufficient energy to become a free electron, leaving a vacancy in the shell. Which of the following events is most likely to occur next in the lattice a short time interval after the electron becomes free?

  • AThe free electron and the vacancy will recombine.
  • BAnother free electron and vacancy will be produced.

Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy.