Doping basics: A pentavalent (group V) impurity introduced into a group IV semiconductor contributes how many valence electrons?

Introduction / Context:
Doping modifies the electrical properties of semiconductors by adding controlled impurities. Pentavalent dopants (group V), such as phosphorus or arsenic, create n-type material by donating electrons.

Given Data / Assumptions:

• Host lattice is group IV (e.g., silicon) with four covalent bonds.
• Dopant is pentavalent (group V): five valence electrons.
• Substitutional doping: dopant replaces a silicon atom in the lattice.

Concept / Approach:
The dopant's five valence electrons form four bonds with neighboring atoms, leaving one extra, loosely bound electron. This electron requires little energy to become a conduction electron, increasing carrier concentration dramatically.

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