PHYSICS
JAMB 2006 - Question 5
Physics 2006 JAMB Past Questions - Question 5: A certain manufacturer wishes to make an n-type semiconductor. Which materials would he select for dopping?
Correct Answer
A
Explanation
An n-type semi conductor is usually formed by dopping the semi conductor with five valent elementTo create an n-type semiconductor, a manufacturer would select materials to introduce specific impurity atoms that have excess electrons to donate into the semiconductor's crystal lattice. These impurity atoms are called donor atoms and are typically from Group V elements in the periodic table.
Commonly used donor impurities for n-type semiconductors include:
1. Phosphorus (P): Phosphorus is one of the most commonly used dopants for creating n-type silicon (Si) semiconductors. Phosphorus has five valence electrons, and when it is introduced into a silicon crystal lattice (which has four valence electrons), it creates an excess electron in the crystal structure, making the material n-type.
2. Arsenic (As): Arsenic is another Group V element used as a donor impurity in semiconductors. Like phosphorus, it has five valence electrons and can introduce excess electrons into the semiconductor lattice.
3. Antimony (Sb): Antimony is another suitable donor impurity. It has five valence electrons and can be used to create n-type semiconductors, particularly in certain compound semiconductors.
4. Bismuth (Bi): Bismuth can also be used as a donor impurity in certain semiconductor materials to make them n-type.
These donor impurities introduce extra electrons into the crystal structure of the semiconductor material, effectively creating more free electrons that can carry current. These excess electrons result in an excess of negative charge carriers, making the material n-type. The exact choice of dopant will depend on the specific semiconductor material being used and its intended applications.