Which of the following is the major impurity added to silicon to create n-type semiconductors?

• A. Phosphorus
• B. Carbon
• C. Aluminum
• D. Boron

Answer: (A)

Verified step by step guidance

1. Understand that n-type semiconductors are created by doping silicon with an element that has more valence electrons than silicon. Silicon has 4 valence electrons.
2. Identify that n-type doping involves adding an element with 5 valence electrons, which will donate extra electrons to the silicon lattice, increasing its conductivity.
3. Review the options: Carbon (4 valence electrons), Aluminum (3 valence electrons), Boron (3 valence electrons), and Phosphorus (5 valence electrons).
4. Recognize that Phosphorus, having 5 valence electrons, is the impurity that donates extra electrons, making it the major impurity used to create n-type semiconductors.
5. Conclude that the correct choice is Phosphorus because it introduces free electrons into the silicon crystal, enhancing its electrical conductivity as an n-type semiconductor.