Question

Mention the difference between p-type and n-type semiconductors.

Hint:

Remember: - p-type → \textbf{Positive (holes)} are majority carriers. - n-type → \textbf{Negative (electrons)} are majority carriers.

Answer 1

Step 1: When a pure semiconductor like silicon is doped with a trivalent impurity (such as boron, aluminium, or gallium), each impurity atom forms covalent bonds with the surrounding silicon atoms but lacks one electron to complete the bonding structure. This creates a deficiency of electrons, known as holes, which act as positive charge carriers. The resulting material is called a p-type semiconductor, where holes are the majority charge carriers.
Step 2: When the same pure semiconductor is doped with a pentavalent impurity (such as phosphorus, arsenic, or antimony), each impurity atom forms covalent bonds with the silicon atoms and contributes an extra electron that is free to move within the crystal lattice. These free electrons act as negative charge carriers. The resulting material is called an n-type semiconductor, where electrons are the majority charge carriers.
Step 3: In both types of doping — p-type and n-type — the number of majority charge carriers (holes in p-type and electrons in n-type) increases significantly compared to the intrinsic (pure) semiconductor. As a result, the electrical conductivity of the semiconductor increases, making it more efficient for use in electronic components such as diodes, transistors, and integrated circuits.