Electrical Engineering XYZ MCQs
Which of below mentioned is a donor to a semiconductor material:
- Divalent
- Pentavalent
- Tetravalent
- Trivalent
Correct answer: 2. Pentavalent
Explanation: Semiconductor materials are crucial components in electronic devices, acting as conductors or insulators depending on the presence of impurities or “dopants”. These dopants are introduced intentionally to modify the conductivity of the semiconductor.
In semiconductors, doping refers to the intentional introduction of impurities into the crystal structure to alter its electrical properties. The most common types of dopants used in semiconductors are:
- Donors: Donor dopants are atoms that have one more valence electron than the atoms they replace in the crystal lattice. These extra electrons are loosely bound and can contribute to the material’s conductivity. Donor dopants are typically from Group V elements of the periodic table because they have five valence electrons. Examples include phosphorus (P), arsenic (As), and antimony (Sb). These elements are pentavalent.So, “Pentavalent” dopants are donors to a semiconductor material.
- Acceptors: Acceptor dopants are atoms that have one less valence electron than the atoms they replace in the crystal lattice. They create “holes” in the crystal structure, which act as positive charge carriers. Acceptor dopants are typically from Group III elements of the periodic table because they have three valence electrons. Examples include boron (B), aluminum (Al), and gallium (Ga). These elements are trivalent.
- Intrinsic: Intrinsic semiconductors are pure semiconductor materials without any intentional doping. They possess a small number of charge carriers due to thermal excitation.
- Extrinsic: Extrinsic semiconductors are semiconductor materials intentionally doped with impurities to alter their conductivity.
Therefore, among the options provided, pentavalent dopants are donors to semiconductor materials.