Increasing the electrical conductivity of a pure silicon or germanium sample

There are several ways to increase the electrical conductivity of a pure silicon or germanium sample. These methods include increasing the temperature, doping it with acceptor impurity, doping it with donor impurity, and shining ultraviolet light on it. Let's discuss each of these methods in detail.

1. Increasing the temperature:
- When the temperature of a semiconductor material like silicon or germanium is increased, the thermal energy provided to the atoms causes them to vibrate more vigorously.
- This increased vibration disrupts the crystal lattice structure and allows more electrons to move freely, increasing the conductivity of the material.
- As a result, the electrical conductivity of a pure silicon or germanium sample increases with an increase in temperature.

2. Doping with acceptor impurity:
- Doping refers to the intentional addition of impurity atoms to a pure semiconductor material.
- When a silicon or germanium crystal is doped with an acceptor impurity such as boron or aluminum, which has fewer valence electrons than the host atom, it creates holes in the crystal lattice.
- These holes act as positive charge carriers, and when an electric field is applied, they can move through the lattice, contributing to electrical conductivity.
- Therefore, doping a pure silicon or germanium sample with an acceptor impurity increases its electrical conductivity.

3. Doping with donor impurity:
- Doping a silicon or germanium crystal with a donor impurity such as phosphorus or arsenic, which has more valence electrons than the host atom, introduces extra electrons into the crystal lattice.
- These extra electrons act as negative charge carriers and significantly increase the electrical conductivity of the material.
- Hence, doping a pure silicon or germanium sample with a donor impurity enhances its electrical conductivity.

4. Shining ultraviolet light:
- When ultraviolet light is shone on a pure silicon or germanium sample, it generates electron-hole pairs through a process called the photoelectric effect.
- The energy provided by the ultraviolet light excites electrons from the valence band to the conduction band, creating free electrons and holes.
- These free charge carriers contribute to the electrical conductivity of the material, increasing its overall conductivity.
- Thus, shining ultraviolet light on a pure silicon or germanium sample can increase its electrical conductivity.

Conclusion:
In conclusion, the electrical conductivity of a pure silicon or germanium sample can be increased by increasing the temperature, doping it with acceptor or donor impurities, and shining ultraviolet light on it. These methods introduce extra charge carriers or disrupt the crystal lattice structure, allowing for better conduction of electricity.