What is the Difference Between Electron Rich and Electron Deficient Impurities?

The key difference between electron-rich and electron-deficient impurities lies in the number of valence electrons they possess and their role in semiconductor technology. Here is a comparison between the two:

Electron-rich impurities:

• Consist of 5 valence electrons.
• Increase the conductivity of semiconductor material.
• When 4 out of the 5 electrons in the impurity atom are used in forming covalent bonds with 4 neighboring atoms, the 5th electron remains extra and becomes delocalized.

Electron-deficient impurities:

• Doped with group 13 elements such as B and Al, which have 3 valence electrons.
• Decrease the conductivity of semiconductor material.
• In electron-deficient impurities, the 4th electron of the lattice atom remains extra and isolated, which can create an electron hole or electron vacancy.

In the context of semiconductors, electron-rich impurities are used to increase the conductivity of the semiconductor material, while electron-deficient impurities are used to decrease the conductivity. Both types of impurities play a crucial role in the functioning of various semiconductor devices.

Comparative Table: Electron Rich vs Electron Deficient Impurities

The main difference between electron-rich and electron-deficient impurities lies in the number of valence electrons they possess. Here is a summary of their characteristics:

In semiconductor technology, impurity atoms are introduced into the semiconductor material to alter its electrical properties. Electron-rich impurities have more valence electrons than the host lattice, resulting in increased conductivity as more electrons become available for conduction. On the other hand, electron-deficient impurities have fewer valence electrons than the host lattice, leading to a decrease in conductivity as electrons are removed from the valence band, creating electron holes or vacancies.